BILLING CODE 4910-13-P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 21, 23, 35, 43, 91, 121, and 135
[Docket No.: FAA-2015-1621; Notice No. 16-01 ]
RIN 2120–AK65
Revision of Airworthiness Standards for Normal, Utility, Acrobatic, and Commuter
Category Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to amend its airworthiness standards for normal, utility,
acrobatic, and commuter category airplanes by removing current prescriptive design
requirements and replacing them with performance-based airworthiness standards. The proposed
standards would also replace the current weight and propulsion divisions in part 23 with
performance- and risk-based divisions for airplanes with a maximum seating capacity of 19
passengers or less and a maximum takeoff weight of 19,000 pounds or less. The proposed
airworthiness standards are based on, and would maintain, the level of safety of the current part
23. Finally, the FAA proposes to adopt additional airworthiness standards to address certification
for flight in icing conditions, enhanced stall characteristics, and minimum control speed to
prevent departure from controlled flight for multiengine airplanes. This notice of proposed
rulemaking addresses the Congressional mandate set forth in the Small Airplane Revitalization
Act of 2013.
DATES: Send comments on or before [INSERT DATE 60 DAYS AFTER DATE OF
PUBLICATION IN THE FEDERAL REGISTER].
ADDRESSES: Send comments identified by docket number FAA-2015-1621 using any of the
following methods:
 Federal eRulemaking Portal: Go to http://www.regulations.gov and follow the online
instructions for sending your comments electronically.
 Mail: Send comments to Docket Operations, M-30; U.S. Department of Transportation
(DOT), 1200 New Jersey Avenue SE, Room W12-140, West Building Ground Floor,
Washington, DC 20590-0001.
 Hand Delivery or Courier: Take comments to Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE, Washington, DC,
between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
 Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: In accordance with 5 USC 553(c), DOT solicits comments from the public to
better inform its rulemaking process. DOT posts these comments, without edit, including any
personal information the commenter provides, to www.regulations.gov, as described in the
system of records notice (DOT/ALL-14 FDMS), which can be reviewed at
http://www.dot.gov/privacy.
Docket: Background documents or comments received may be read at
http://www.regulations.gov at any time. Follow the online instructions for accessing the docket
or go to the Docket Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
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FOR FURTHER INFORMATION CONTACT: For technical questions concerning this
action, contact Lowell Foster, Regulations and Policy, ACE-111, Federal Aviation
Administration, 901 Locust St., Kansas City, MO 64106; telephone (816) 329-4125; e-mail
lowell.foster@faa.gov.
SUPPLEMENTARY INFORMATION: Later in this preamble, under the Additional
Information section, we discuss how you can comment on this proposal and how we will handle
your comments. This discussion includes related information about the docket, privacy, and the
handling of proprietary or confidential business information. We also discuss how you can get a
copy of this proposal and related rulemaking documents.
All sections of part 23 would contain proposed revisions, except the FAA would not
make any substantive changes to the following sections: §§ 23.1457, Cockpit Voice Recorders,
and 23.1459, Flight Data Recorders. The only proposed changes to § 23.1459 would be for the
purpose of aligning part 23 references. These sections are nevertheless included in this proposed
revision for context.
Table of Contents
I. Executive Summary
A. Purpose and History of the Proposed Performance-Based Standards
B. Summary of Major Provisions
1. Performance Standards and Airplane Crashworthiness
2. Loss of Control
3. Icing Certification Standards
C. Cost and Benefits
II. Authority for this Rulemaking
III. Background
A. Part 23 History
B. New Safety Requirements
C. Benefits for the Existing Fleet
D. Conforming Amendments and Other Minor Amendments
E. Public Policy Implementation
1. Regulatory Planning and Review
2. Consensus Standards
3. International Cooperation Efforts for Reorganizing Part 23
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F. Means of Compliance
G. FAA Strategic Initiatives
IV. Discussion of Proposal
A. Reorganization of Airworthiness Standards Based on Risk and Performance
B. Introduction of Simple Airplanes
C. Establishing Performance-Based Standards and the Use of Means of Compliance
D. Crashworthiness as an Illustration of the Benefits of Performance-Based Regulations
E. Additional Requirements to Prevent Loss of Control
F. Additional Requirements for Flight in Icing Conditions
G. Production of Replacement and Modification Articles
V. Key Terms and Concepts Used in this Document
VI. Discussion of the Proposed Regulatory Amendments
A. Part 23, Airworthiness Standards
1. Subpart A – General
2. Subpart B – Flight
3. Subpart C – Structures
4. Subpart D – Design and Construction
5. Subpart E – Powerplant
6. Subpart F – Equipment
7. Subpart G – Flightcrew Interface and Other Information
8. Appendices to Part 23
B. Miscellaneous Amendments
1. Production of Replacement and Modification Articles (§ 21.9)
2. Designation of Applicable Regulations (§ 21.17)
3. Issuance of Type Certificate: Primary Category Aircraft (§ 21.24)
4. Flight Tests (§ 21.35)
5. Instructions for Continued Airworthiness and Manufacturer's Maintenance Manuals
Having Airworthiness Limitations Sections (§ 21.50)
6. Designation of Applicable Regulations (§ 21.101)
7. Applicability (§ 35.1)
8. Fatigue Limits and Evaluation (§ 35.37)
9. Altimeter System Test and Inspection (Appendix E to Part 43)
10. Powered Civil Aircraft with Standard Category U.S. Airworthiness Certificates:
Instrument and Equipment Requirements (§ 91.205)
11. Restricted Category Civil Aircraft: Operating Limitations (§ 91.313)
12. Increased Maximum Certification Weights for Certain Airplanes Operated in Alaska
(§ 91.323)
13. Second In Command Requirements (§ 91.531)
14. Additional Emergency Equipment (§ 121.310)
15. Additional Airworthiness Requirements (§ 135.169)
VII. Regulatory Notices and Analyses
A. Regulatory Evaluation Summary
B. Initial Regulatory Flexibility Determination
C. International Trade Impact Assessment
D. Unfunded Mandates Assessment
E. Paperwork Reduction Act
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F. International Compatibility and Cooperation
G. Environmental Analysis
H. Regulations Affecting Intrastate Aviation in Alaska
VIII. Executive Order Determination
A. Executive Order 13132, Federalism
B. Executive Order 13211, Regulations that Significantly Affect Energy Supply, Distribution,
or Use
IX. Additional Information
A. Comments Invited
B. Availability of Rulemaking Documents
Appendix 1 to the Preamble—Current to Proposed Regulations Cross-Reference Table
Appendix 2 to the Preamble—Abbreviations and Acronyms Frequently Used In This
Document
I. Executive Summary
A. Purpose and History of the Proposed Performance-Based Standards
Part 23 of Title 14 of the Code of Federal Regulations (14 CFR) prescribes airworthiness
standards for issuance and amendment of type certificates for airplanes with a passenger-seating
configuration of 19 or less and a maximum certificated takeoff weight of 19,000 pounds or less.
Airplanes certificated under part 23 are typically used for recreation, training, personal travel,
and limited commercial applications.
The current part 23 airworthiness standards are largely prescriptive, meaning that they
describe detailed design requirements, and are based on airplane designs from the 1950’s and
1960’s. As a result of this prescriptive framework, the FAA often requires a design approval
applicant seeking to incorporate new or innovative technology to provide additional
documentation that typically results in the FAA’s issuance of special conditions, exemptions, or
equivalent level of safety (ELOS) findings.1 The FAA recognizes that these additional
1
Special conditions give the manufacturer permission to build the aircraft, engine or propeller with additional
capabilities not addressed in the regulations. A petition for exemption is a request to the FAA by an individual or
entity asking for relief from the requirements of a regulation. Equivalent level of safety findings are made when
literal compliance with a certification regulation cannot be shown and compensating factors exist which can be
shown to provide an equivalent level of safety. 14 CFR parts 11 and 21 provides information on special conditions
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procedures and requirements are costly to the FAA and industry, act as barriers to certification,
and discourage innovation. Therefore, to encourage the installation of new safety-enhancing
technology and streamline the certification process, the FAA proposes replacing the prescriptive
requirements found in the current part 23 with performance-based standards.
The FAA believes this proposed rulemaking would maintain the level of safety associated
with current part 23, while providing greater flexibility to applicants seeking certification of their
airplane designs. By doing so, this proposed rulemaking would hasten the adoption of safety
enhancing technology in type-certificated products while reducing regulatory time and cost
burdens for the aviation industry and FAA. This proposed rulemaking would also reflect the
FAA’s safety continuum philosophy,2 which balances the need for an acceptable level of safety
with the societal burden of achieving that level safety, across the broad range of airplane types
certificated under part 23.
This proposed rulemaking is the result of an effort the FAA began in 2008 to re-evaluate
the way it sets standards for different types of airplanes. Through this effort, a joint FAA and
industry team produced the Part 23 Certification Process Study3 (CPS), which reviewed the life
cycle of part 23 airplanes to evaluate certification processes and develop recommendations. Two
key recommendations were to (1) reorganize part 23 based on airplane performance and
complexity rather than the existing weight and propulsion divisions, and (2) permit the use of
consensus standards as a means to keep pace with rapidly increasing design complexity in the
aviation industry.
and exemptions. FAA Order 8110-112A provides standard procedures for issue paper and equivalent level of safety
memoranda.
2
The FAA’s safety continuum philosophy is that one level of safety may not be appropriate for all aviation. The
FAA accepts higher levels of risk, with correspondingly fewer requirements for the demonstration of compliance,
when aircraft are used for personal transportation.
3
See www.regulations.gov (Docket # FAA-2015-1621)
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In 2010, with the CPS as a foundation, the FAA conducted a Part 23 Regulatory Review
and held meetings with the public and industry to gain input on revising part 23. These meetings
confirmed strong public and industry support for the CPS recommendations to revise part 23.
In 2011, the FAA formed the Part 23 Reorganization ARC to consider further the CPS
recommendation to reorganize part 23 based on airplane performance and complexity and to
investigate the use of consensus standards. The ARC recommendations,4 published in 2013, echo
the CPS recommendations.
On January 7, 2013, Congress passed the Federal Aviation Modernization and Reform
Act of 20125 (Public Law 112-95; 49 U.S.C. 40101 note) (FAMRA), which requires the
Administrator, in consultation with the aviation industry, to assess the aircraft certification and
approval process. Based on the ARC recommendations and in response to FAMRA, the FAA
began work on this proposed rulemaking on September 24, 2013. Subsequently, on November
27, 2013, Congress passed the Small Airplane Revitalization Act of 2013 (Public Law 113-53,
49 U.S.C. 44704 note) (SARA), which requires the FAA to issue a final rule revising the
certification requirements for small airplanes by—

Creating a regulatory regime that will improve safety and decrease certification
costs;

Setting safety objectives that will spur innovation and technology adoption;

Replacing prescriptive rules with performance-based regulations; and

Using consensus standards to clarify how safety objectives may be met by
specific designs and technologies.
4
5
See www.regulations.gov (Docket # FAA-2015-1621)
http://www.gpo.gov/fdsys/pkg/CRPT-112hrpt381/pdf/CRPT-112hrpt381.pdf
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The FAA believes that the performance-based-standards component of this proposal
complies with the FAMRA and the SARA because it would improve safety, reduce regulatory
compliance costs, and spur innovation and the adoption of new technology. This proposal would
replace the weight-and propulsion-based prescriptive airworthiness standards in part 23 with
performance- and risk-based airworthiness standards for airplanes with a maximum seating
capacity of 19 passengers or less and a maximum takeoff weight of 19,000 pounds or less. The
proposed standards would maintain the level of safety associated with the current part 23, while
also facilitating the adoption of new and innovative technology in general aviation (GA)
airplanes.
B. Summary of Major Provisions
This proposal to revise part 23 has two principal components: establishing a
performance-based regulatory regime and adding new certification standards for loss of control
(LOC) and icing. Where the FAA proposes to establish new certification requirements, these
requirements would be adopted within the same performance-based framework proposed for part
23 as a whole.
1. Performance Standards and Airplane Crashworthiness
Airplane crashworthiness and occupant safety is an example of how moving towards
performance-based standards and providing greater flexibility to industry would increase
aviation safety. Although the FAA has over the years incrementally amended part 23 to enhance
occupant safety, these amendments have focused on individual system components, rather than
the safety of the system as a whole. By building greater flexibility into FAA regulations
governing crash testing, this proposal would allow the aviation industry to develop and
implement novel solutions.
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2. Loss of Control
One proposed revision to part 23 would improve general aviation safety by creating
additional certification standards to reduce LOC accidents. Inadvertent stalls resulting in airplane
LOC are the most common cause of small airplane fatal accidents. These LOC accidents
frequently occur in the traffic pattern or at low altitudes, where the airplane is too low for a pilot
to recover control before impacting the ground. The proposed revisions would require applicants
to use new design approaches and technologies to improve airplane stall characteristics and pilot
situational awareness to prevent such accidents.
3. Icing Certification Standards
Another proposed revision to part 23 would improve GA safety by addressing severe
icing conditions. In the 1990s, the FAA became aware of the need to expand the icing conditions
considered during the certification of airplanes and turbine aircraft engines. In particular, the
FAA determined that revised icing certification standards should include Supercooled Large
Drops (SLD)6, mixed phase, and ice crystals.
This proposed rule would require manufacturers that choose to certify an airplane for
flight in SLD to demonstrate safe operations in SLD conditions. For those manufacturers who
choose instead to certify an airplane with a prohibition against flight in SLD conditions, this
proposed rule would require a means for detecting SLD conditions and showing the airplane can
safely exit such conditions. Industry has indicated that these requirements would not impose
significant additional cost burden on industry because many manufacturers already have
equipped recent airplanes with technology to meet the standards for detecting and exiting SLD
conditions in accordance with current FAA guidance.
6
SLD conditions include freezing drizzle and freezing rain, which contain drops larger than those specified in
appendix C to part 25, and can accrete aft of wing leading edge ice protection systems.
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C. Cost and Benefits
The goal of this proposal is to create a cost-effective approach to certification that
facilitates the adoption of new safety enhancing technologies and allows for alternative means of
compliance. The FAA has analyzed the benefits and costs associated with this NPRM. If the
proposed rule saves only one human life, for example, by improving stall characteristics and stall
warnings, that alone would result in benefits outweighing the costs. The following table shows
these results.
Estimated Benefits and Costs from 2017 to 2036 (2014 $ Millions)
Costs Safety Benefits + Cost Savings = Total Benefits
Total
$3.9
$19.6 + $12.6 = $32.2
Present value
$3.9
$6.2 + $5.8 = $12.0
Accordingly, the FAA has determined that the proposed rule would be cost beneficial.
II. Authority for this Rulemaking
The FAA’s authority to issue rules on aviation safety is found in Title 49 of the United
States Code. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle
VII, Aviation Programs, describes in more detail the scope of the agency’s authority.
This rulemaking is promulgated under the authority described in Subtitle VII, Part A,
Subpart III, Section 44701. Under that section, the FAA is charged with promoting safe flight of
civil airplanes in air commerce by prescribing minimum standards required in the interest of
safety for the design and performance of airplanes. This regulation is within the scope of that
authority because it prescribes new performance-based safety standards for the design of normal,
utility, acrobatic, and commuter category airplanes.
Additionally, this rulemaking addresses the Congressional mandate set forth in the Small
Airplane Revitalization Act of 2013 (Public Law 113-53; 49 U.S.C. 44704 note) (SARA).
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Section 3 of SARA requires the Administrator to issue a final rule to advance the safety and
continued development of small airplanes by reorganizing the certification requirements for such
airplanes under part 23 to streamline the approval of safety advancements. SARA directs that the
rule address specific recommendations of the 2013 Part 23 Reorganization Aviation Rulemaking
Committee (ARC).
III. Background
The range of airplanes certificated under part 23 is diverse in terms of performance
capability, number of passengers, design complexity, technology, and intended use. Currently,
each part 23 airplane’s certification requirements are determined by reference to a combination
of factors, including weight, number of passengers, and propulsion type. The resulting divisions
(i.e., normal, utility, acrobatic, and commuter categories) historically were appropriate because
there was a clear relationship between the propulsion and weight of the airplane and its
associated performance and complexity.
Technological developments have altered the dynamics of that relationship. For example,
high-performance and complex airplanes now exist within the weight range that historically was
occupied by only light and simple airplanes. The introduction of high-performance, lightweight
airplanes required subsequent amendments of part 23 to include more stringent and demanding
standards—often based on the part 25 requirements for larger transport category airplanes—to
ensure an adequate level of safety for airplanes under part 23. The unintended result is that some
of the more stringent and demanding standards for high-performance airplanes now apply to the
certification of simple and low-performance airplanes.
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A. Part 23 History
Part 23 originated from performance-based requirements developed by the Bureau of Air
Commerce and the Civil Aeronautics Administration in the 1930s. These regulations were
contained in specific Civil Air Regulations (CAR) for the certification of aircraft (i.e., CAR 3, 4,
and 4a). These requirements, along with various bulletins and related documents, were
subsequently revised and first published as 14 CFR part 23 in 1964 (29 FR 17955, December 18,
1964). Over the past five decades and after numerous amendments, part 23 has evolved into a
body of highly complex and prescriptive requirements attempting to codify specific design
requirements, address specific problems encountered during prior certification projects, and
respond to specific recommendations from the National Transportation Safety Board (NTSB).
Although the intent of the prescriptive language contained in current part 23 was to
increase the level of safety, prevent confusion, and clarify ambiguities, the current regulations
have also restrained manufacturers’ ability to employ new designs and testing methodologies.
The FAA believes moving towards performance-based standards should significantly reduce or
eliminate barriers to innovation and facilitate the introduction of new safety-enhancing
technologies.
In 2008, the FAA conducted a review of part 23 by initiating the Part 23 CPS.
Collaborating with industry, the team’s challenge was to determine the future of part 23, given
today’s current products and anticipated future products. The team identified opportunities for
improvements by examining the entire life cycle of a part 23 airplane. The CPS recommended
reorganizing part 23 using criteria focused on performance and design complexity. The CPS also
recommended that the FAA implement general airworthiness requirements, with the means of
compliance defined in industry consensus standards standards. In 2010, following the publication
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of the Part 23 CPS, the FAA held a series of public meetings to seek feedback concerning the
findings and recommendations. Overall, the feedback was supportive of and in some cases
augmented the CPS recommendations.
One notable difference between the CPS findings and the public feedback was the
public’s request that the FAA revise part 23 certification requirements for simple, entry-level
airplanes. Over the past two decades, part 23 standards have become more complex as industry
has generally shifted towards correspondingly complex, high-performance airplanes. This
transition has placed an increased burden on applicants seeking to certificate smaller, simpler
airplanes. Public comments requested that the FAA focus on reducing the costs and time burden
associated with certificating small airplanes by restructuring the requirements based on perceived
risk. The safety risk for most simple airplane designs is typically low.
On August 15, 2011, the Administrator chartered the Part 23 Reorganization ARC to
consider the following CPS recommendations—

Recommendation 1.1.1 - Reorganize part 23 based on airplane performance and
complexity, rather than the existing weight and propulsion divisions; and

Recommendation 1.1.2 - Certification requirements for part 23 airplanes should
be written on a broad, general, and progressive level, segmented into tiers based
on complexity and performance.
The ARC’s recommendations took into account the FAMRA, which requires the
Administrator, in consultation with the aviation industry, to assess the aircraft certification and
approval process. The purpose of the ARC’s assessment was to develop recommendations for
streamlining and reengineering the certification process to improve efficiency, reduce costs, and
ensure that the Administrator can conduct certifications and approvals in a manner that supports
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and enables the development of new products and technologies and the global competitiveness of
the United States aviation industry7. FAMRA also directs the Administrator to consider the
recommendations from the Part 23 Certification Process Study.8
ARC membership represented a broad range of of stakeholder perspectives, including
U.S. and international manufacturers, trade associations, and foreign civil aviation authorities.
The ARC was supported by FAA subject matter experts from all affected lines of business, from
design and production certification to continued airworthiness and alterations. The following
table identifies ARC participants:
U.S. Manufacturers
Bendix-King
Cessna
Continental Motors
Cub Crafters
Garmin
Hawker Beechcraft
Honeywell
Kestrel
Rockwell-Collins
Quest
Tamarack Aero
TruTrak
U.S. Organizations
Aircraft Electronics
Aircraft Owners and Pilots
ASTM
Association (AEA)
Association (AOPA)
General Aviation
National Air Traffic
Experimental Aircraft
Manufacturers Association
Controllers Association
Association (EAA)
(GAMA)
(NATCA)
RTCA
SAE
International Manufacturers
Dassault Falcon
Diamond
Flight Design
Rotax
Socata
International Civil Aviation Authorities
European Aviation Safety
Transport Canada Civil
National Civil Aviation
Agency (EASA)
Aviation (TCCA)
Agency of Brazil (ANAC)
Civil Aviation Administration
Civil Aviation Authority of
of China (CAAC)
New Zealand.
Avidyne
Cirrus
GAMI
Honda
Lockheed Martin
Sensenich Propellers
Each member or participant on the committee represented an identified segment of the
aviation community, with the authority to speak for that segment. The ARC also invited subject
7
8
Section 312(c)
Section 312 (b)(6)
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matter experts to support specialized working groups and subgroups, as necessary. These
working groups developed recommendations and briefed the ARC as a whole. The ARC then
collectively discussed and voted to accept or reject the recommendations. All of the
recommendations included in the ARC’s report had overwhelming majority agreement.
The ARC noted the prevailing view within industry was that the only way to reduce the
program risk, or business risk, associated with the certification of new airplane designs was to
avoid novel design approaches and testing methodologies. The certification of new and
innovative products today frequently requires the FAA’s use of ELOS findings, special
conditions, and exemptions. These take time, resulting in uncertainty and high project costs. The
ARC emphasized that although industry needs from the outset to develop new airplanes designed
to use new technology, current certification costs inhibit the introduction of new technology. The
ARC identified prescriptive certification requirements as a major barrier to installing safety‐
enhancing modifications in the existing fleet and to producing newer, safer airplanes.
The ARC also examined the harmonization of certification requirements among the FAA
and foreign civil aviation authorities (CAAs), and the potential for such harmonization to
improve safety while reducing costs. Adopting performance-based safety regulations that
facilitate international harmonization, coupled with internationally accepted means of
compliance, could result in both significant cost savings and the enabling of safety-enhancing
equipment installations. The ARC recommended that internationally accepted means of
compliance should be reviewed and voluntarily accepted by the appropriate aviation authorities,
in accordance with a process established by those authorities. Although each CAA would be
capable of rejecting all or part of any particular means of compliance, the intent would be to have
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full civil authority participation in the creation of the means of compliance to ease acceptance of
the means of compliance.
B. New Safety Requirements
The performance-based standards proposed in this NPRM are designed to maintain the
level of safety provided by current part 23 requirements. The current part 23 weight and
propulsion divisions were based on assumptions that do not reflect the diversity of performance
capabilities, design complexity, technology, intended use, and seating capacity of today’s new
airplane designs, or the future airplane designs that will become possible as technology continues
to evolve. The FAA would therefore replace the current divisions with certification levels 1 thru
4, low performance, high performance, and simple. Furthermore, this would replace the current
divisions within the individual sections with technical and operational capabilities focused on the
technical drivers (e.g., stall speed, Visual Flight Rules (VFR) and Instrument Flight Rules (IFR)
operations, pressurization). These types of technical and operational criteria would apply a more
appropriate set of standards to each airplane, and continue to accommodate the wide range of
airplane designs within part 23.
To begin, the FAA proposes to eliminate commuter, utility, and acrobatic airplane
categories from part 23, retaining only a normal category for all new part 23 type certificated
airplane design approvals. The differences between normal, utility, and acrobatic categories are
currently very limited and primarily affect airframe structure requirements. Proposed part 23
would continue to allow a normal category airplane to be approved for aerobatics, provided the
airplane is certificated for the safety factors and defined limits of aerobatic operations.
In addition, the FAA proposes that airplanes approved for spins be certificated to
aerobatic standards. Under the current § 23.3(b), the utility category provides airplanes
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additional margin for the more stringent inertial structural loads resulting from intended spins
and other maneuvers. An airplane designed with traditional handling qualities and designed to
allow spin training is more susceptible to inadvertent departure from controlled flight. The FAA
therefore believes that maintaining the current utility category for spin and limited aerobatic
maneuver capable airplanes would negate the largest, single safety gain expected from this
rulemaking action—the significant reduction in inadvertent stall-related departures from
controlled flight.
Under this proposal, airplanes already certificated in the commuter, utility, and acrobatic
categories would continue to fall within those categories. Each new airplane design, however,
would be subject to varying levels of analysis, based on the potential risk and performance of the
airplane’s design. A more rigorous standard, such as currently applied to commuter category
airplanes, would apply to higher risk and higher performance airplanes.
The proposed requirements would also include new enhanced standards for resistance to
departure from controlled flight. Recognizing that the largest number of fatal accidents for part
23 airplanes results from LOC in flight, the FAA proposes to update certification standards to
address these risks. LOC happens when an airplane enters a flight regime outside its normal
flight envelope or performance capabilities and develops into a stall or spin, an event that can
surprise the pilot. A pilot’s lack of awareness of the state of the airplane in flight and the
airplane’s low-speed handling characteristics are the main causal factors of LOC accidents.
Furthermore, stall and departure accidents are generally fatal because an airplane is often too low
to the ground for the pilot to recover.. Improving safety that reduces stall and LOC accidents
would save lives. The FAA is therefore proposing new rules for stall characteristics and stall
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warnings that would result in airplane designs more resistant to inadvertently departing
controlled flight.
Another type of low-speed LOC accident that occurs in significant numbers involves
minimum control speed (VMC) in light twin-engine airplanes. Virtually all twin-engine airplanes
have a VMC that allows directional control to be maintained after one engine fails. This speed is
usually above the stall speed of the airplane. However, light twin-engine airplanes typically have
limited climb capability on one engine. In the accidents reviewed by the ARC and FAA, often in
these situations, pilots attempted to maintain a climb or maintain altitude, which slowed the
airplane down, rather than looking for the best landing site immediately, maintaining control the
whole way. If the airplane’s speed drops below VMC, the pilot can lose control. In tying the
minimum control speed to the stall speed of the airplane, pilots, rather than attempting to
maintain climb and lose directional control, would instead react appropriately with stall training
techniques, resulting in a controlled descent rather than a loss of directional control. This
requirement will be on new airplanes and should add little or no cost because it can be designed
in from the start.
The FAA also has identified a need for improved certification standards related to
operations in severe icing conditions. More specifically, in the 1990’s, the FAA became aware of
the need to expand the icing conditions considered during the certification of airplanes and
turbine aircraft engines, to increase flight safety during some severe icing conditions. The 1994
accident in Roselawn, Indiana, involving an Avions de Transport Regional ATR 72 series
airplane in SLD conditions, brought to public and governmental attention safety concerns about
the adequacy of the existing icing certification standards.
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As a result of the 1994 accident, and consistent with related NTSB recommendations, in
1997 the Administrator tasked the Aviation Rulemaking Advisory Committee (ARAC) (62 FR
64621, December 8, 1997) with defining SLD, mixed phase, and ice crystal icing environments,
and designing corresponding safety requirements for those conditions. In June 2000, the ARAC’s
task was revised to address only transport category airplanes. More recent events, such as an Air
France Airbus model A330-203 AF4479 accident, in 2009, highlighted the negative effects of ice
crystals on airspeed indication systems and turbojet engines.
The FAA ultimately published amendments 25-140 (79 FR 65507, November 4, 2014)
and 33-34 (79 FR 65507, November 4, 2014), Airplane and Engine Certification Requirements
in Supercooled Large Drop, Mixed Phase, and Ice Crystal Icing Conditions that expanded parts
25 and 33 icing requirements, but did not amend part 23 requirements. On February 19, 2010, the
Administrator chartered a Part 23 Icing ARC to review and recommend SLD, mixed phase, and
ice crystal icing conditions regulations and guidance for part 23. In February 2012, the Part 23
Icing ARC formally identified a need to improve the part 23 regulations to ensure safe operation
of airplanes and engines in SLD and ice crystal conditions.10 In particular, the Part 23 Icing ARC
recommended adopting most of the part 25 icing rules, including the requirement to show either
that an airplane can safely fly in SLD conditions, or that it can detect and safely exit SLD. The
proposals in this NPRM incorporate the recommendations of the Part 23 Icing ARC.
C. Benefits for the Existing Fleet
The proposed revisions would benefit owners and modifiers of existing part 23 airplanes,
as well as airplane designers and manufacturers. Both currently and under this proposal,
9
See www.regulations.gov (Docket # FAA-2015-1621) , Air France A330-203, Flight AF 447 Final Accident
Report
10
See www.regulations.gov (Docket # FAA-2015-1621)
19
airplanes may be modified by: (1) an alteration to an individual airplane; (2) a supplemental type
certificate (STC) for multiple airplanes, or (3) an amendment to an original type design via an
amended type certificate (TC). This proposal would streamline each of these methods for
modifying airplanes.
The proposed change to § 21.9 would facilitate FAA approval of low-risk equipment
produced for installation in type-certificated airplanes, thereby streamlining the process for
owners to upgrade equipment on their individual airplanes. An example of how this change
would facilitate safety improvements is the installation of inexpensive weather display systems
in the cockpits of small airplanes. These systems allow a pilot to view current weather conditions
along the planned flight route and at the destination airport, avoiding unexpected or deteriorating
weather conditions. Since these systems are not required and because they represent low safety
risk from failure, the FAA believes streamlining its approval process to produce them for use in
existing airplanes could lower costs and increase availability of these systems.
The proposed changes in the rules would also streamline the process for design approval
holders applying for a type design change, or for a third party modifier applying for an STC, to
incorporate new and improved equipment in a model or several models of airplanes. Since the
revised part 23 standards would be much less prescriptive, the certification process for
modifications would be simplified. Certification of an amended TC or STC under the proposed
part 23 standards would require fewer special conditions or exemptions, lowering costs and
causing fewer project delays.
20
D. Conforming Amendments and Other Minor Amendments
References to part 23 appear throughout the FAA’s current regulations. Accordingly, the
FAA proposes to amend the following parts for consistency with the proposed revisions to part
23: part 21, part 35, part 43, part 91, part 121, and part 135.
The FAA also proposes to revise part 21 to simplify the approval process for low-risk
articles. Specifically, the FAA proposes amending § 21.9 to allow FAA-approved production of
replacement and modification articles using methods not listed in § 21.9(a). This proposed
change is intended to reduce constraints on the use of non-required, low risk articles, such as
carbon monoxide detectors and weather display systems.
E. Public Policy Implementation
The intent of this NPRM is to reduce regulatory barriers by establishing a system based
on safety-focused performance requirements and FAA acceptance—as a means of compliance—
of consensus standards. FAA-accepted consensus standards would add clarity to the certification
process and streamline FAA involvement in the development of means of compliance.
Additionally, adopting performance standards would significantly reduce the complexity of part
23. Furthermore, the introduction of airplane certification levels based on risk (i.e., number of
passengers) and performance (i.e., speed) would advance the FAA’s effort to introduce riskbased decision-making and better align with the FAA’s safety continuum philosophy. Together,
the FAA believes these changes would allow the FAA to provide appropriate oversight based on
the safety continuum and would restore a simple and cost effective certification process based on
proven engineering practices.
21
1. Regulatory Planning and Review
In accordance with applicable executive orders, the FAA has determined that the
proposed revisions to part 23 are the most cost-beneficial way of achieving the agency’s
regulatory objectives. This is because the proposal would relieve industry of a significant
regulatory burden while maintaining or improving the level of safety under the regulations. In
particular, Executive Order 12866, Regulatory Planning and Review (58 FR 51735, October 4,
1993), and Executive Order 13563, Improving Regulation and Regulatory Review (76 FR 3821,
January 21, 2011), direct each Federal agency to propose or adopt a regulation only upon a
reasoned determination that the benefits of the intended regulation justify its costs. This proposal
is not an economically “significant regulatory action” as defined in section 3(f) of Executive
Order 1286611 and it satisfies Executive Order 13563 by protecting public health, welfare, safety,
while promoting economic growth, innovation, competitiveness, and job creation.
Under the above-referenced executive orders, when an agency determines that a
regulation is the best available method of achieving its regulatory objective, the agency must
design the regulation or regulations in the most cost-effective manner. In doing so, each agency
must consider incentives for innovation, consistency, predictability, enforcement and compliance
costs (to the government, regulated entities, and the public), flexibility, distributive impacts, and
equity. Each agency must identify and assess alternative forms of regulation and shall specify, to
the extent feasible, performance objectives, rather than specifying the behavior or manner of
compliance that regulated entities must adopt. This proposal meets these requirements because it
would implement performance objectives rather than a prescriptive methodology, thereby
reducing time and cost burdens on industry and increasing opportunities for innovation.
22
Executive Order 13610, Identifying and Reducing Regulatory Burdens (77 FR 28469,
May 10, 2012) reiterates the direction from Executive Order 13563 in stating that our regulatory
system must measure, and seek to improve, the actual results of regulatory requirements. To
promote this goal, agencies are to engage in periodic review of existing regulations, and are
required to develop retrospective review plans to examine existing regulations in order to
determine whether any such regulations should be modified, streamlined, expanded, or repealed.
The purpose of this requirement is to make the agency's regulatory program more effective or
less burdensome in achieving the regulatory objectives. In response to Executive Orders13563
and 13610, agencies have developed and made available for public comment retrospective
review plans. Both the Part 23 Reorganization ARC and this Part 23 Rulemaking Project are on
the Department of Transportation’s retrospective review plans.
2. Consensus Standards
Section 3(c) of SARA requires the Administrator, when developing regulations, to
comply with the requirements of the National Technology Transfer and Advancement Act of
199512 (Public Law 104-113; 15 U.S.C. 272 note) (NTTAA) and to use consensus standards to
the extent practicable while maintaining traditional methods for meeting part 23. Section 12(d) of
the NTTAA directs Federal agencies to use, either by reference or by inclusion, voluntary
consensus standards in lieu of government-mandated standards, except where inconsistent with
law or otherwise impractical. The Office of Management and Budget (OMB) Circular A-119,13
Federal Participation in the Development and Use of Voluntary Consensus Standards and
Conformity Assessment Activities, provides guidance to Executive agencies in implementing the
requirements of the NTTAA.
12
13
http://www.gpo.gov/fdsys/pkg/PLAW-104publ113/pdf/PLAW-104publ113.pdf
https://www.whitehouse.gov/omb/circulars_a119/
23
Accordingly, the FAA proposes to accept consensus standards as a means of compliance
with the proposed part 23 performance-based regulations. The use of consensus standards would
be one means of compliance with the performance-based standards of the proposed part 23.
Compliance with the current prescriptive provisions within current part 23 would be yet another
means of compliance available under this proposal. Applicants would still have the option to
propose their own means of compliance as they do today. The process for reviewing new means
of compliance would not change substantially from the process in place today.
Although a consensus standard works in some cases, the Part 23 Reorganization ARC
expressed concerns that a consensus standard could be biased in favor of a few large
manufacturers and thereby create an unfair competitive advantage. OMB Circular A-119 also
cautions regulators to avoid such potential biases. The FAA notes that industry groups associated
with the Part 23 Reorganization ARC identified ASTM International (ASTM) as the appropriate
organization to initiate the development of consensus standards, and that ASTM permits any
interested party to participate in the committees developing consensus standards. The FAA
expects other consensus standards bodies to allow similar opportunities for interested parties to
participate in their standards-development work. In addition to consensus standards and the
current prescriptive design standards in part 23, any individual or organization may develop its
own proposed means of compliance that may be submitted to the FAA for acceptance.
3. International Cooperation Efforts for Reorganizing Part 23
Executive Order 13609, Promoting International Regulatory Cooperation (77 FR 26413,
May 4, 2012), promotes international regulatory cooperation to meet shared challenges and
reduce, eliminate, or prevent unnecessary differences in regulatory requirements. Consistent with
this Order, the FAA’s proposal would address unnecessary differences in regulatory
24
requirements between the United States and its major trading partners. The U.S. GA industry has
repeatedly informed the FAA of the high costs to address differences between the airworthiness
requirements of the FAA and foreign CAAs. The FAA believes this proposal has the potential to
achieve long-term harmonization at an unprecedented level, and should result in a significant
savings for both U.S. manufacturers exporting products abroad and foreign manufacturers
exporting products to the U.S. The FAA requests comments regarding the potential cost savings.
The work of the Part 23 Reorganization ARC forms the foundation of the proposed
changes to part 23. From the onset, the ARC was a cooperative, international effort.
Representatives from several foreign CAAs14 and international members from almost every GA
manufacturer of airplanes and avionics participated in the Part 23 Reorganization ARC. Several
international light-sport aircraft manufacturers, who were interested in certificating their
products using part 23 airworthiness standards, also participated. In addition to recommending
changes to part 23, the ARC developed proposals to help reduce certification costs through more
international standardization of certification processes and reducing or eliminating redundant
certification activities associated with foreign certification.
After the ARC issued its report, the FAA, foreign CAAs, and industry continued to work
together to refine the ARC rule language until the FAA began drafting the NPRM in December
2014. This included formal meetings in July and November of 2014. EASA, Transport Canada,
other foreign authorities, and industry offered significant contributions to these efforts.
In addition, the CAAs from Europe, Canada, Brazil, China, and New Zealand are
working to produce rules similar to those contained in this proposal. EASA, for example,
published an Advance Notice of Proposed Amendment (A-NPA) 2015-06 on March 27, 2015,
14
CAAs included participants from Brazil, Canada, China, Europe, and New Zealand.
25
which sets forth EASA’s concept for its proposed reorganization of CS-23, and on which the
FAA provided comments. Like the FAA’s current proposal, EASA’s A-NPA was also based on
the proposed ARC language with the goal of harmonization. Both proposals would adopt
performance-based standards that facilitate the use of consensus standards as a means of
compliance.
F. Means of Compliance
This proposal would allow type certificate applicants to use FAA-accepted means of
compliance to streamline the certification process. This proposal, however, is shaped by two
concerns raised in the Part 23 Reorganization ARC. First, the rule needs to clearly state that any
applicant must use a means of compliance accepted by the Administrator when showing
compliance with part 23. The FAA emphasizes that any means of compliance would require
FAA review and acceptance by the Administrator. Second, although a means of compliance
developed by a consensus standards body (i.e., ASTM, SAE, RTCA, etc.) may be available, any
individual or organization would also be able to submit its own means of compliance
documentation to the Administrator for consideration and potential acceptance.
The FAA anticipates that both individuals and organizations would develop acceptable
means of complying with the proposed performance standards. The industry groups associated
with the ARC discussed the development of consensus-based standards and selected ASTM as
the appropriate organization to initiate the effort. A standards organization such as ASTM could,
for example, generate a series of consensus-based standards for review, acceptance, and public
notice of acceptance by the FAA. The ASTM standards would be one way, but not the only way,
to demonstrate compliance with part 23.
26
Using means of compliance documents to satisfy compliance with the proposed
performance-based rules would diminish the need for special conditions, ELOS findings, and
exemptions to address new technology advancements. Once the Administrator accepted a means
of compliance, it could be used in future certification applications unless formally rescinded.
Incorporating the use of consensus standards as a means of compliance with performance-based
regulations would provide the FAA with the agility to more rapidly accept new technology as it
develops, leverage industry experience and expectations to develop of new means of compliance
documents, and encourage the use of harmonized means of compliance among the FAA,
industry, and foreign CAAs. Although an applicant would not be required to use previously
accepted means of compliance documents, doing so would streamline the certification process by
eliminating the need for the FAA to develop an issue paper to address the certification of new
technology. Proposed Advisory Circular 23.10, Accepted Means of Compliance, would describe
a process for applicants to submit proposed means of compliance to the FAA for acceptance by
the Administrator.
The Part 23 Reorganization ARC was also concerned that specialists in the industry could
argue for complex means of compliance when the FAA would accept a simpler or more cost
effective approach. To address these concerns, the FAA would continue to allow applicants to
propose their own means of compliance when the larger industry standard may be the
appropriate level of safety for one but not all certification levels, consistent with the guidance in
OMB Circular A-119, which reminds the regulator that the government is responsible to the
public for setting the appropriate level of safety and avoiding any unfair competitive advantage.
Additionally, the FAA proposes to continue to allow the use of the prescriptive means of
compliance currently codified in part 23 as yet another alternative means of compliance with
27
proposed part 23. This would not apply, however, to the proposed new requirements, such as
§§ 23.200, 23.215, and 23.230.
G. FAA Strategic Initiatives
The FAA’s Strategic Initiatives 2014-2018 communicates FAA goals for addressing the
challenges presented by the changing aviation industry and how the FAA intends to make the
U.S. aviation system safer and smarter, and raise the bar on safety. Specifically, one strategic
initiative is for the FAA to embrace and implement risk-based decision making approaches,
which build on safety management principles to address emerging safety risks using consistent,
data-informed approaches to make smarter, quicker system-level decisions. By establishing
performance-based regulations, coupled with industry standards, this proposed rulemaking
would provide a calibrated and globally competitive regulatory structure. This new approach
would increase safety in general aviation by enabling and facilitating innovation and the
implementation of safety enhancing designs in newly certificated products.
This rulemaking effort also directly supports the FAA’s Global Leadership Initiative, by
encouraging global harmonization and the consistent use of regulations, standards, and practices
for general aviation airplanes.
IV. Discussion of Proposal
A. Reorganization of Airworthiness Standards Based on Risk and Performance
The FAA proposes replacing the current weight and propulsion-based airplane
certification divisions with airplane certification and performance levels based on the number of
potential passengers and the performance of the airplane. The FAA believes this proposed
regulatory change would better accommodate the wide range of airplanes certificated under part
23, thereby reducing certification risk, time, and costs.
28
Historically, turbine-powered airplanes were assumed to fly at or above 18,000 feet
(5,486 meters) and at high speeds, whereas piston engine airplanes were assumed to fly below
18,000 feet (5,486 meters) and at lower speeds. Today, with advancements in aviation
technology, these general design and performance assumptions may not be valid. Furthermore,
the current regulations do not account for airplanes equipped with new technologies, such as
electric propulsion systems, which may have features that are entirely different from piston and
turbine engines. For these reasons, the FAA is proposing regulations based on airplane
performance and potential risk rather than on assumptions about specific technologies. These
proposed standards would be appropriate to each specific airplane design.
Certification of airplanes under part 23 would either be conducted using airplane
certification levels based on maximum passenger seating configuration and airplane performance
levels based on speed, or occur as so-called “simple airplanes” that are low-speed airplanes with
a stalling speed (VSO) ≤ 45 Knots Calibrated Airspeed (KCAS) approved only for VFR
operations. The FAA proposes the following airplane certification levels:

Level 1 – for airplanes with a maximum seating configuration of 0 to 1
passengers, including simple airplanes.

Level 2 – for airplanes with a maximum seating configuration of 2 to 6
passengers.

Level 3 – for airplanes with a maximum seating configuration of 7 to 9
passengers.

Level 4 – for airplanes with a maximum seating configuration of 10 to 19
passengers.
29
B. Introduction of Simple Airplanes
The regulations contained in part 23 have gradually become more focused on highperformance, turbine-powered airplanes, and this emphasis has become a barrier to the efficient
certification and introduction to market of new entry-level, simple airplanes. The Part 23
Reorganization ARC specifically noted that current part 23 does not have appropriate standards
for the certification of entry-level airplanes.
The FAA proposes to define “simple airplanes” in § 23.5 to recognize the entry-level
airplane. Simple airplanes would be limited to airplane designs that allow transport of no more
than one passenger (in addition to the pilot), are limited to VFR operations, and have both a low
top speed and a low stall speed. These airplanes are similar to EASA’s Certification
Specification-Very Light Aeroplanes (CS-VLA), which are currently imported to the U.S. and
certificated as special class airplanes in accordance with 14 C.F.R. § 21.17(b). The proposed
change would allow these airplanes to be certified as normal category airplanes under part 23.
The FAA believes that permitting certification of simple airplanes would allow more
certified entry-level airplanes to enter the marketplace. The FAA expects simple airplanes to be a
more basic sublevel within proposed certification level 1, but recognizes that because of
similarities between simple and non-simple airplanes within certification level 1, creating this
category may be unnecessary. For this reason, the FAA is specifically asking for comments
concerning the utility of creating a separate, simple airplane sublevel.
C. Establishing Performance-Based Standards and the Use of Means of Compliance
The Part 23 Reorganization ARC was aware the Administrator has accepted as evidence
of compliance various manufacturers’ internal design standards in the past, and the ARC
recommended expressly stating that option in the proposal. Proposed § 23.10, Accepted means of
30
compliance, would allow individual persons or companies to submit their internal standards as
means of compliance for consideration by the Administrator. Proposed § 23.10 would also
require an applicant to show the FAA how it would demonstrate compliance with this part using
a means of compliance, which may include consensus standards accepted by the Administrator.
It would further require an applicant requesting acceptance of a means of compliance to provide
the means of compliance to the FAA in a form and manner specified by the Administrator. In
addition, proposed § 23.10 specifically recognizes the use of consensus standards as a means of
compliance that could be acceptable to the Administrator. If this information is proprietary in
nature, it would be afforded the same protections as are applied today in certification
applications submitted under 14 CFR part 21.
The phrase “means of compliance” may have different connotations depending on its
context. Historically, the FAA has treated an applicant’s demonstration of compliance as a
means of compliance. Alternatively, as indicated by sec. 3(b)(4) of the SARA, consensus
standards may constitute a means of compliance that can address new and novel designs and
technologies. In other words, as suggested by the SARA, an applicant would develop a design to
satisfy a performance-based standard, and the design is the means of complying with the
standard.
Currently, an applicant for a type certificate must show the FAA how it satisfies the
applicable airworthiness standards. The applicant submits the type design, test reports, and
computations necessary to show compliance. The applicant approaches the FAA and enters into
negotiations regarding what constitutes an adequate demonstration—testing or analysis. The
FAA anticipates that, under the proposed framework, standards developed by consensus
standards bodies would provide a pre-existing means by which any applicant may demonstrate
31
compliance with the corresponding performance-based requirements. For example, the proposed
fuel system requirements would be broad enough to certificate airplanes with electric propulsion
systems in which batteries and fuel cells are used as fuel. Airplanes incorporating these systems
cannot currently be certificated without applying for special conditions or exemptions.
Elements of this proposal are already in place today. Industry standards bodies like
RTCA, SAE, ASTM, and the European Organization for Civil Aviation Equipment (EUROCAE)
have already developed detailed means of compliance documents that an applicant for a type
certificate may use to demonstrate compliance with our regulatory requirements in 14 CFR parts
23, 25, 27, and 29. For decades, the FAA has identified these means of compliance documents as
an acceptable means of complying with our regulatory requirements. This proposal would build
on and expand this aspect of our regulations by also transitioning part 23 towards a regulatory
framework based on performance standards.
D. Crashworthiness as an Illustration of the Benefits of Performance-Based Regulations
One area where the implications of a change from prescriptive to performance-based
requirements are most evident is in the demonstration of crashworthiness. The current part 23
crashworthiness and occupant safety requirements are based on seat and restraint technology
used in the 1980’s. Currently, an applicant demonstrates crashworthiness by a sled test. Under
the proposed standards, an applicant would not necessarily have to perform a sled test, but could
instead employ a different method accounting for many other factors, several of which are
described below. The FAA is imposing no new requirements, but would, under this proposal,
provide greater flexibility to adopt new safety-testing methodologies and, ultimately, more
advanced safety technologies.
32
The FAA proposes to allow greater flexibility with respect to the testing and
demonstration, similar to advancements made in the automotive industry over the past 30 years.
The proposed regulations would facilitate evaluation of the entirety of a crashworthiness
system—namely, the interaction of all crashworthiness features—rather than requiring an
evaluation of discrete, individual parameters. A system’s ability to protect occupants can be
better understood by evaluating it as a complete system, and using that greater understanding to
develop and implement new technologies. Such an evaluation could include analyses of
important survivability factors identified by the NTSB, including occupant restraints, survivable
volume, energy-absorbing seats, and seat retention. These proposed crashworthiness standards
would not necessarily prevent accidents, but should improve survivability.
The NTSB produced a series of reports in the 1980s that evaluated over 21,000 GA
airplane crashes between 1972 and 1981. The NTSB General Aviation Crashworthiness Project15
evaluated airplane orientation, impact magnitudes, and survival rates and factors to provide
information supporting changes in crashworthiness design standards for GA seating and restraint
systems. The NTSB reports also established conditions approximating survivable accidents and
identified factors that would have the largest impact on safety. Amendment 23-36 (53 FR 30802,
August 15, 1988) to part 23 referenced these reports for dynamic seats but did not adopt a
systems-evaluation approach.
The NTSB reports identified several factors that, working together as a system, should
result in a safer airplane. The assessment also indicated, however, that shoulder harnesses offer
the most immediate individual improvement for safety. The FAA codified the shoulder harnesses
requirement in amendments 23-19 (42 FR 20601, June 16, 1977) and 23-32 (50 FR 46872,
15
See www.regulations.gov (Docket # FAA-2015-1621)
33
November 13, 1985) for newly manufactured airplanes. The FAA also issued policy statement
ACE-00-23.561-01, Methods of Approval of Retrofit Shoulder Harness Installations in Small
Airplanes,16 dated September 19, 2000, to streamline the process for retrofitting older airplanes.
Current part 23 requires occupant restraints to maintain integrity, stay in place on the occupant
throughout an event, properly distribute loads on the occupant, and restrain the occupant by
mitigating interaction with other items in the cabin. Newer technologies that enhance or
supplement the performance of these restraints, such as airbags, are now being considered for
inclusion in designs. The use of airbags has greatly increased passenger safety in automobiles, by
offering protection in much more severe impacts and in impacts from multiple directions. The
proposed performance standards would enable the use of these technologies.
Survivable volume is another critical factor in crashworthiness. Survivable volume is the
ability of the airframe to protect the occupants from external intrusion, or the airplane cabin
crushing during and after an accident. There were several observed accidents in the NTSB study
where conventional airplane construction simply crushed an otherwise restrained occupant.
Crashworthiness regulations have never included survivable volume as a factor, except in some
instances in which an airplane turns over. Airplane designs should provide the space needed for
the protection and restraint of the occupants. This is one of the first steps in the analysis of
airplane crashworthiness.
Data from the NTSB General Aviation Crashworthiness Project suggested that energyabsorbing seats that protect the occupant from vertical impact loads could enhance occupant
survivability and prevent serious injury, thereby enhancing odds for exiting the airplane and
preventing many debilitating long-term injuries. The FAA established dynamic seat testing
16
See www.regulations.gov (Docket # FAA-2015-1621)
34
requirements in amendment 23-36 for airplanes certificated under part 23. Energy absorbing
seats have a smaller impact than some other safety factors because accident impacts with large
vertical components tend to have lower odds of survival. Nevertheless, energy attenuation from
vertical forces, both static and dynamic, has been important to crashworthiness regulations for
the past 25 years. Seats may crush or collapse, but must remain attached to the body of the
airplane. Coupling the seat performance to the rest of the airframe response is important to the
enhancement and understanding of occupant survivability. The FAA believes allowing designers
to consider airframe deformation would result in more accurate floor impulses, which relate to
simulated crash impact, and may allow for evaluation for crash impulses in multiple directions.
The NTSB also identified seat retention as another basic building block for airplane
crashworthiness. The NTSB reports show more than a quarter of otherwise-survivable accidents
included instances where the seats broke free at the attachment to the airplane, resulting in
fatalities or serious injuries. Dynamic seat testing requirements address the ability of seat
assemblies to remain attached to the floor, even when the floor shifts during impact. Pitching and
yawing of the seat tracks during dynamic seat tests demonstrates the gimbaling and flexibility of
the seat.
The FAA believes that, under this proposal, all of these crashworthiness factors could be
incorporated into future testing methodologies and thereby increase the survivability of accidents
in part 23 certificated airplanes. This proposed part 23 amendment would authorize design
approval applicants to use these technologies and testing methodologies to enhance occupant
safety.
35
E. Additional Requirements to Prevent LOC
LOC continues to be the leading cause of fatal GA accidents. The FAA identified 74
accidents caused by stall or LOC between January 2008 and December 2013. These accidents,
which are listed in Appendix IV of the Part 23 Regulatory Evaluation17, represent the type of
accidents that could be prevented by the proposed new stall and LOC requirements.
The FAA proposes to add requirements in §§ 23.200 and 23.215 to prevent LOC
accidents. Inadvertent stalls resulting in airplane LOC cause a large number of small airplane
fatal accidents. These LOC accidents in the traffic pattern or at low altitudes often result in
fatalities because the airplane is too low to the ground for the pilot to recover control. The FAA
therefore believes it can improve safety by requiring applicants to use new approaches to
improve airplane stall characteristics to prevent such accidents.
Another type of low-speed LOC accident that occurs in significant numbers involves VMC
in light twin-engine airplanes. Virtually all twin-engine airplanes have a VMC that allows
directional control to be maintained after one engine fails. This speed is typically above the stall
speed of the airplane. However, light twin-engine airplanes also typically have limited climb
capability on one engine. Moreover, after the failure of one engine, pilots often instinctively tend
to try to maintain a climb or maintain altitude, which slows the airplane down. If the speed drops
below VMC, the pilot can lose control of the airplane. Because pilots tend to be more aware of the
airplane’s stall speed, the FAA proposes in § 23.200 that certification levels 1 and 2 multiengine
airplanes would be required to have a VMC that does not exceed the stall speed of the airplane for
each configuration. The FAA believes this proposed requirement would provide a higher level of
safety than current § 23.149. The FAA requests comments on this proposal.
17
See www.regulations.gov (Docket # FAA-2015-1621)
36
The FAA also proposes new requirements in § 23.215 for airplane stall characteristics
and stall warning that would result in airplane designs more resistant to inadvertently stalling and
departing controlled flight. These proposed requirements would increase the level of safety over
the current requirements. At the same time, the FAA proposes to eliminate the spin recovery
requirement in the current rules for normal category airplanes. The FAA believes the spin
recovery requirement is unnecessary for normal category airplanes because the vast majority of
inadvertent stalls leading to spin entry occur below a safe altitude for spin recovery. However,
airplanes certificated for aerobatics would still have to meet spin recovery requirements.
The FAA also proposes to address pilot stall awareness by requiring warnings that are
more effective and by allowing new approaches to improve pilot awareness of stall margins.
These warnings could be as simple as angle of attack or energy awareness presentations, or
sophisticated envelope protection systems that add a forward force to the pilot’s controls as the
airplane speed and attitude approach stall.
F. Additional Requirements for Flight in Icing Conditions
The FAA proposes to implement the Part 23 Icing ARC’s recommendations in §§ 23.230,
23.940 and 23.1405, to allow an applicant the option of certifying an airplane to operate in SLD
icing conditions. To do so, an applicant would be required to meet the same safety standards in
SLD icing conditions as currently demonstrated for part 23 airplanes in the icing conditions
defined in appendix C to part 25.
Currently, the FAA does not certify part 23 airplanes to operate in SLD icing conditions,
also known as freezing drizzle and freezing rain. Instead, current part 23 icing regulations require
airplane performance, flight characteristics, systems, and engine operation to be demonstrated in
the icing conditions defined in appendix C to part 25, which does not contain SLD icing
37
conditions. In 2012, prior to the Part 23 Reorganization ARC, the Part 23 Icing ARC
recommended revising part 23 to include SLD icing requirements in subparts B, E, and F (Flight,
Powerplant, and Equipment, respectively).
If an applicant chooses not to certify an airplane in SLD icing conditions, proposed
§ 23.230 would require the applicant to demonstrate that SLD icing conditions could be detected
and safely exited. A means of compliance for SLD detection and exit may be found in FAA
Advisory Circular 23.1419-2D, Certification of Part 23 Airplanes for Flight in Icing
Conditions.18 The service history of airplanes certificated under part 23 and certified to the latest
icing standards has shown that AC 23.1419-2D provides an adequate level of safety for detecting
and safely exiting SLD icing conditions. Industry has indicated that these requirements would
not impose an additional burden because many manufacturers have already equipped recent
airplanes to meet the standards for detecting and exiting SLD in accordance with current FAA
guidance. Proposed § 23.230, along with proposed § 23.940, Powerplant ice protection, and
§ 23.1405, Flight in icing conditions, and their respective means of compliance, address NTSB
safety recommendations A-96-54 and A-96-56. The following table provides a summary of the
proposed icing regulations.
Part 23 Type
Certificate Limitations
Not certified for flight in
icing conditions.
Certified for flight in
icing conditions, but
18
Proposed Icing Regulations
Engine Protection (§ 23.940)
Airframe and System
Protection, Performance and
Flight Characteristics
Requirements (§§ 23.230,
23.1300, and 23.1405)
Safe in part 25, App C
None, except pitot heat required if
conditions, ground ice fog, and airplane certified for flight in
falling/blowing snow
instrument meteorological
conditions (IMC)
Safe in part 25, App C
Safe in part 25, App C conditions.
conditions, ground ice fog, and Can detect SLD and safely exit
See www.regulations.gov (Docket # FAA-2015-1621)
38
prohibited for flight in
SLD.
Certified for flight in
icing conditions and
SLD.
falling/blowing snow
Safe in part 25, App C
Safe in part 25, App C conditions
conditions, ground ice fog, and and SLD.
falling/blowing snow, and SLD.
G. Production of Replacement and Modification Articles
The Part 23 Reorganization ARC recommended simplifying certification requirements
for non-required systems and equipment, with an emphasis on improvement in overall fleet
safety from the prevailing level. In the past, the FAA has not established different production
requirements for required and non-required equipment that may enhance safety, or for articles
whose improper operation or failure would not cause a hazard. The current requirements for
producing articles and representing those articles as suitable for installation on type-certificated
products are well suited for articles manufactured in accordance with a product’s TC or STC, as
well as for TSO and PMA parts. However, they may unnecessarily constrain the production of
non-required, low risk articles.
Current standards for the production approval of these articles can create a barrier for
their installation in the existing fleet of aircraft. Examples of such articles include carbon
monoxide detectors, weather display systems, clocks, small hand-held fire extinguishers, and
flashlights. In many cases, these articles are “off-the-shelf” products. It is frequently difficult for
a person to install these articles on a type-certificated aircraft because the level of design and
production details necessary for these articles to meet the provisions of current § 21.9, as
expected for more critical articles, are frequently unavailable.
The FAA is therefore proposing to revise § 21.9, Replacement and Modification Articles,
to provide applicants with an alternative method to obtain FAA approval to produce replacement
and modification articles. This proposed change would allow a production approval applicant to
39
submit production information for a specific article, without requiring the producer of the article
to obtain approval of the article’s design or approval of its quality system. The FAA intends to
use the flexibility provided by this proposal to streamline the approval process for non-required
safety enhancing equipment and other articles that pose little or no risk to aircraft occupants and
the public. The FAA requests comments on this proposal, and particularly is interested in
comments regarding whether the proposed change would safely facilitate retrofit of low risk
articles and whether there are alternative methods to address the perceived retrofit barrier.
V. Key Terms and Concepts Used in this Document
The proposal includes a number of terms introduced into the regulations for the first time.
These terms may be used to replace existing prescriptive requirements or may explain other
terms that have had longstanding use in the aircraft certification process, but in context of this
rulemaking proposal, the FAA wants to specify its meaning. These terms are intended to set forth
and clarify the safety intent of the proposed rules. Although certain terms may differ from those
currently in use, these differences are not intended to increase the regulatory burden on an
applicant unless specifically stated. The FAA’s intent is that the proposed requirements
incorporating these new terms not change the intent, understanding, or implementation of the
original rule unless that requirement has been specifically revised in the proposal, such as is the
case for requirements governing stall characteristics. To assist applicants in understanding the
intent of the proposal, these terms are discussed below:
Airplane Certification Level – A division used for the certification of airplanes that is
associated directly with the number of passengers on the airplane. Airplane certification levels
would be established to implement the agency’s concept of certificating airplanes using a process
that recognizes a safety continuum.
40
Airplane Performance Level – Maximum airspeed divisions that are intended, along with
airplane certification levels, to replace current weight and propulsion divisions used for the
certification of airplanes. Current propulsion-based divisions assume that piston engine airplanes
are slower than turbine-powered airplanes. Current weight-based divisions assume that heavier
airplanes are more complex and would be more likely to be used in commercial passenger
carriage than lighter airplanes. These assumptions are no longer valid. Airplane certification
based on performance levels would apply regulatory standards appropriate to airplane’s
performance and complexity.
Departure Resistant – For the purposes of this NPRM, departure resistant refers to stall
characteristics that make it very difficult for the airplane to depart controlled flight. Most fatal
stall or spin accidents start below 1000 feet above ground level and do not actually spin, but start
a yawing and rolling maneuver to enter the spin called a post stall gyration. In these low-altitude
accidents, the airplane typically hits the ground before completing one turn. Therefore, the
important safety criterion is preventing the airplane from exhibiting stall characteristics that
could result in a departure from controlled flight.
Entry-Level Airplane – A two or four-place airplane typically used for training, rental,
and by flying clubs. Historically, most of these airplanes have four cylinder engines with less
than 200 horsepower. These airplanes typically have fixed-gear and fixed-pitch propellers, but
may also have retractable landing gear and constant speed propellers. Entry-level airplanes
typically cannot be used to train pilots to meet the requirements to operate a complex aircraft, as
that term is defined for airman certification purposes.
Equivalent Level of Safety (ELOS) Finding – A finding made by the accountable aircraft
certification directorate when literal compliance with a certification requirement cannot be
41
shown and compensating factors in the design can be shown to provide a level of safety
equivalent to that established by the applicable airworthiness standard.
Fuel – any source used by the powerplant to generate its power.
Hazard – Any existing or potential condition that can lead to injury, illness or death;
damage to or loss of a system, equipment, or property; or damage to the environment. A hazard
is a condition that is a prerequisite to an accident or an incident. (Cf. Order VS 8000.367,
Appendix A)
Issue Paper – A structured means for describing and tracking the resolution of significant
technical, regulatory, and administrative issues that occur during a certification project. The issue
paper process constitutes a formal communication vehicle for addressing significant issues
among an applicant, the FAA, and if applicable, the validating authority (VA) or certificating
authority (CA) for type validation programs. An issue paper may also be used to address novel or
controversial technical issues.
Means of Compliance – A documented procedure used by an applicant to demonstrate
compliance to a performance or outcome-based standard. Similar to an Advisory Circular (AC),
a means of compliance is one method, but not the only method, to show compliance with a
regulatory requirement. Additionally, if a procedure is used as a means of compliance, it must be
followed completely to maintain the integrity of the means of compliance.
Performance- or Outcome-Based Standard – A standard that states requirements in terms
of required results, but does not prescribe any specific method for achieving the required results.
A performance-based standard may define the functional requirements for an item, operational
requirements, or interface and interchangeability characteristics.
42
Pilot or Flightcrew – This is used generically throughout the proposed part 23 because
part 23 has airplanes approved for single pilot operations as well as and two flightcrew members.
For most airplanes certificated under part 23 that are single pilot, applicants should consider pilot
and flightcrew to be interchangeable.
Prescriptive Design Standard – Specifies a particular design requirement, such as
materials to be used, how to perform a test, or how an item is to be fabricated or constructed. (Cf.
OMB Circular A-119 Section 5.f.)
Safety Continuum – The concept that one level of safety is not appropriate for all aviation
activities. Accordingly, higher levels of risk, with corresponding requirements for less rigorous
safety demonstrations for products, are accepted as aircraft are utilized for more personal forms
of transportation.
Survivable Volume – The airplane cabin’s ability to resist external intrusion or structural
collapse during and after impact. The ability to resist is usually represented as a stiffer design
around the cabin (not unlike a racecar roll cage) that is generally stronger than the surrounding
structure. While the airframe may deform or disintegrate and attenuate impact energy, the cabin
of the airplane will still maintain its integrity and protect the occupants restrained within. During
otherwise survivable accident scenarios, including rollover, this structure should maintain its
shape under static and dynamic loading conditions.
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VI. Discussion of the Proposed Regulatory Amendments
A. Part 23, Airworthiness Standards
1. Subpart A—General
a. General Discussion
The FAA proposes eliminating the utility, acrobatic, and commuter categories for future
airplanes certificated under part 23. The FAA also proposes to change from weight and
propulsion divisions to performance and risk divisions. This would address the wide range of
airplanes to be certificated under part 23 and enhance application of the safety continuum
approach. Appendix 1 of this preamble contains a cross-reference table detailing how the current
regulations are addressed in the proposed part 23 regulations.
b. Specific Discussion of Changes
i. Proposed § 23.1, Applicability and Definition
Proposed § 23.1 would prescribe airworthiness standards for the issuance of type
certificates, and changes to those certificates, for airplanes in the normal category. Current
§ 23.3, Airplane categories, defines normal category as airplanes that have a seating
configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of
12,500 pounds or less, and intended for nonacrobatic operation. Proposed § 23.1 would delete
references to utility, acrobatic, and commuter category airplanes, and paragraph (b) would not
include the current reference to procedural requirements for showing compliance. The reference
to procedural requirements for showing compliance is redundant with the requirement in § 21.21,
Issue of type certificate: normal, utility, acrobatic, commuter, and transport category aircraft;
manned free balloons; special classes of aircraft; aircraft engines; propellers, to show
44
compliance. Proposed § 23.1 would also add three definitions specific to part 23: 1) continued
safe flight and landing, 2) designated fire zone, and 3) empty weight.
ii. Proposed § 23.5, Certification of Normal Category Airplanes
Proposed § 23.5 would apply certification in the normal category to airplanes with a
passenger-seating configuration of 19 or less and a maximum certificated takeoff weight of
19,000 pounds or less. Proposed § 23.5 would also establish certification levels based on the
passenger seating configuration and airplane performance levels based on speed.
The diversity of airplanes certificated under part 23 is large relative to performance,
numbers of passengers, complexity, technology, and intended use. Airplane certification
requirements under part 23 are currently determined using a combination of weight, numbers of
passengers, and propulsion type. These divisions historically were appropriate because there was
a clear relationship between the propulsion and weight of the airplane and its associated
performance and complexity. Recent technological developments have altered the dynamics of
this relationship. High-performance and complex airplanes now exist within the weight range
that was typical for light and simple airplanes. Furthermore, current part 23 has evolved to meet
the additional regulatory requirements resulting from the introduction of high-performance
airplanes. This has resulted in the introduction of more stringent and demanding requirements in
the lower weight airplanes such as the use of 14 CFR part 25 based requirements for simple,
single-engine turbine airplanes. The result is that some of the current requirements have become
more demanding for simple and low-performance airplanes.
The FAA proposes replacing the current part 23 weight and propulsion divisions because
they were based on assumptions that do not always fit the large diversity of airplane
performance, complexity, technology, intended use, and seating capacity encompassed in today’s
45
new airplane designs. Also, the current divisions may not be appropriate to address unforeseen
designs of the future. The commuter category, originally intended for the certification of
airplanes over 12,500 pounds and up to 19 passengers, is currently used for larger business jets
with less than ten passengers. The proposed certification and performance level approach, while
different from the current divisions, would capture the safety intent of part 23 more appropriately
than the current propulsion and weight divisions.
The FAA proposes replacing the current divisions with specific technical and operational
capabilities by addressing, for example, stall speed, VFR/ IFR operation, pressurization, etc., that
represent the actual technical drivers for current prescriptive requirements. These types of design
specific technical and operational criteria would be more appropriate for a means of compliance
document where a complete range of airplane designs could be addressed. The FAA proposes
that high-speed, multiengine airplanes and multiengine airplanes over 12,500 pounds should
continue meeting the equivalent commuter category performance-based requirements. The
proposed performance requirements would be based on number of passengers (certification
level) and airplane performance (performance level); not weight or propulsion type.
The FAA proposes to eliminate commuter, utility, and acrobatic airplane categories in
part 23, retaining only normal category for all new part 23 type certificated airplane design
approvals. The FAA believes this action would not affect the existing fleet of small airplanes.
For example, the commuter category was originally introduced into part 23 to apply to a 10 to 19
passenger, multiengine airplane, operated in scheduled service under 14 CFR parts 121 and 135.
However, new airplanes certified under part 23 can no longer be used in scheduled service under
part 121 because § 121.157, Aircraft certification and equipment requirements, paragraph (h),
requires a part 25 certification for newly type certificated airplanes. The majority of airplanes
46
recently certified in the commuter category are multiengine business jets. Additionally, the
certification category of commuter can be confused with the same term in the operating rules
because the term is defined differently in the certification and operation rules. The FAA
recognizes that moving away from weight and propulsion divisions would result in changes for
the criteria used to determine when to apply the existing commuter category certification
requirements using the numbers of passenger seats (excluding crewmember seats), performance,
and technical divisions proposed in this NPRM. The FAA proposes the following airplane
certification levels:

Level 1 – for airplanes with a maximum seating configuration of 0 to 1
passengers.

Level 2 – for airplanes with a maximum seating configuration of 2 to 6
passengers.

Level 3 – for airplanes with a maximum seating configuration of 7 to 9
passengers.

Level 4 – for airplanes with a maximum seating configuration of 10 to 19
passengers.
The differences between normal, utility, and acrobatic categories are currently very
limited and primarily affect airframe structure requirements. Proposed part 23 would still allow a
normal category airplane to be approved for aerobatics provided the airplane was certified to
address the factors affecting safety for the defined limits for that kind of operation. Currently, the
utility category provides airplanes additional margin for the more stringent inertial structural
loads resulting from intended spins and the additional maneuvers stated in the requirements of
the utility category in § 23.3(b). The FAA proposes that airplanes approved for spins be
47
certificated to aerobatic standards. An airplane designed with traditional handling qualities and
designed to allow spin training is more susceptible to inadvertent departure from controlled
flight. The FAA believes that maintaining the current utility category for airplanes approved for
spins and limited aerobatic maneuvers would negate the single largest safety gain expected from
this rulemaking action—the significant reduction in inadvertent stall-related departures from
controlled flight.
Proposed § 23.5(c) would categorize the performance level of an airplane as low speed or
high speed. The combination of certification levels and performance levels is intended to provide
divisions that address the actual safety concern of occupant numbers and performance, for
example, future designs using novel propulsion methods. The FAA proposes the following
airplane performance levels:

Low speed – for airplanes with a design cruising speed (VC) or maximum
operating limit speed (VMO) ≤ 250 KCAS (or MMO ≤ 0.6).

High speed – for airplanes with a VC or VMO > 250 KCAS (or MMO > 0.6).
Proposed § 23.5(d) would identify a simple airplane as one with a certification level 1, a
VC or VMO ≤ 250 KCAS (and MMO ≤ 0.6), and a VSO ≤ 45 KCAS, and approved only for VFR
operations. The FAA proposes a simple airplane as equivalent to airplanes certificated under
EASA’s current CS-VLA. In most cases, EASA’s CS-VLA requirements are identical to the
proposed corresponding part 23 requirements and have been proposed in the requirements for
certification level 1 airplanes. The FAA considered using the CS-VLA standards in combination
with the proposed part 23 certification standards for all certification level 1, low-speed airplanes.
However, the FAA believes that there are several requirements in CS-VLA that are not
appropriate for all certification level 1, low-speed airplanes, such as no requirement for a type
48
certified engine in CS-VLA. Therefore, the FAA proposes creating a limited certification and
performance level for simple airplanes. Simple airplanes would be a subset of certification level
1, low-speed airplanes and would have a VSO ≤ 45 KCAS and would only be approved for VFR
operations.
In accordance with the FAA’s objective to remove weight and propulsion divisions from
the rules and use performance and certification divisions, the proposed requirements applicable
to the certification of simple airplanes would not completely conform to the criteria EASA uses
to certificate very light airplanes. The FAA proposes that simple airplanes would constitute a
subset of certification level 1, low-speed airplanes that would be required to have a low stall
speed limit and a VFR limitation in order to maintain a level of safety appropriate for these
airplanes. The FAA believes that creating the simple certification level would encourage
manufacturers of light-sport and experimental aircraft kits to pursue type certificates for their
airplane designs without encountering the administrative, procedural or regulatory barriers
existing in current part 23, while allowing innovative technology in those designs.
The FAA considered allowing airplanes that meet the consensus standards applicable to
the certification of special light-sport aircraft to be included in proposed part 23. However, the
FAA decided that this would not be in the best interest of the GA community because it could
result in the elimination of the special light-sport aircraft category. There are advantages in the
certification of special light-sport aircraft, such as self-certification, that would not be available if
the aircraft were type certificated under part 23. This proposal would instead enable a simpler
path to part 23 certification for airplanes that meet the definition of a light-sport aircraft and wish
to pursue a type of certificate for business reasons.
49
The FAA expects simple airplanes to be more basic than the proposed certification level
1, low-speed airplanes. A simple airplane is a certification level 1, low-speed airplane with a stall
speed limit of 45 KCAS that would be limited to VFR operations. The FAA recognizes that a
simple airplane level would have characteristics very similar to certification level 1, low-speed
airplanes, and that creating this category may be unnecessary. For this reason, the FAA is
specifically asking for comments concerning the value of creating a separate, simple airplane
level.
iii. Proposed § 23.10, Accepted Means of Compliance
Proposed § 23.10 would require an applicant to show the FAA how it would demonstrate
compliance with this part using a means of compliance, which may include consensus standards,
accepted by the Administrator. Proposed § 23.10 would also require an applicant requesting
acceptance of a means of compliance to provide the means of compliance to the FAA in a form
and manner specified by the Administrator.
Proposed § 23.10 would create flexibility for applicants in developing means of
compliance and also specifically identify consensus standards as a means of compliance the
Administratory may find acceptable. The Part 23 Reorganization ARC proposed using consensus
standards for the detailed means of compliance to the fundamental safety requirements in
proposed part 23. As discussed in the International Harmonization Efforts section of this NPRM,
the intent of this proposal is to create a regulatory architecture for part 23 that is agile enough to
keep up with innovation. Allowing the use of consensus standards would accomplish this goal.
The Part 23 Reorganization ARC recommended creating this proposed section to identify
specifically the means of compliance documents developed by industry, users such as large
flight schools,the interested public, and the FAA, that an applicant could use in developing a
50
certification application.. The ARC expressed two concerns that led to the creation of the
proposed requirement. First, applicants need to use a means of compliance accepted by the
Administrator when showing compliance to part 23. Second, while a consensus standards body
(i.e., ASTM, SAE, RTCA, etc.) developed means of compliance document may be available,
individuals or organizations may also submit their own means of compliance documentation to
the Administrator for consideration and potential acceptance. Additionally, the FAA wants to
ensure applicants understand that an applicant-developed means of compliance document would
require FAA review and acceptance by the Administrator.
The FAA anticipates that individuals or organizations would develop acceptable means
for complying with the proposed performance standards. A standards organization such as
ASTM, for example, could generate a series of consensus-based standards for review,
acceptance, and public notice of acceptance by the FAA. The ASTM standards could be one
way, but not the only way, to demonstrate compliance with part 23. Other consensus standard
bodies such as RTCA and SAE are currently focused on developing standards for aircraft
components and appliances.
The proposed airworthiness standards would allow airplanes to be certificated at different
airplane certification levels. For example, software integrity levels appropriate for a certification
level 1 airplane may not be appropriate for a certification level 4 airplane. Additionally, the
takeoff performance of an airplane might be evaluated differently for an airplane intended to be
certificated at different airplane certification levels. An applicant seeking certification of a
certification level 1 airplane with a takeoff distance of 200 feet, for example, would not need to
establish the takeoff distance with the same degree of accuracy as wouldan applicant seeking
certification of a certification level 4 high-speed airplane with a takeoff distance of 4,000 feet.
51
By using means of compliance documents to show compliance with the proposed
performance-based rules, the need for special conditions, ELOS findings, and exemptions to
address new technology advancements would diminish. Once the Administrator accepted a
means of compliance, it may be used for future applications for certification unless formally
rescinded. Allowing the use of consensus standards as a means of compliance to performancebased regulations would provide the FAA with the agility necessary to more rapidly accept new
technology, leverage industry expectations in the development of new means of compliance
documents, and provide for the use of harmonized means of compliance among the FAA,
industry, and foreign CAAs. While an applicant would not be required to use previously
accepted means of compliance documents, their use would streamline the certification process by
eliminating the need to develop an issue paper to address the certification of new technology.
Proposed AC 23.1019, Accepted Means of Compliance, would provide guidance for applicants
on the process applicants would follow to submit proposed means of compliance to the FAA for
consideration by the Administrator.
The Part 23 Reorganization ARC expressed concerns that a consensus standard could be
biased in favor of a few large manufacturers and would create an unfair competitive advantage.
The FAA notes that any interested party may participate in the ASTM committees developing
consensus standards thereby, mitigating this concern. The FAA expects that other consensus
standards bodies would allow similar opportunities for interested parties to participate in their
standards development work. Additionally, any individual or organization could develop its own
means of compliance and submit it to the FAA for acceptance by the Administrator. The other
risk identified by the Part 23 Reorganization ARC was that specialists in the industry could argue
19
See www.regulations.gov (Docket # FAA-2015-1621)
52
for complex means of compliance when the FAA would accept a simpler or more cost effective
approach. However, the FAA would continue to allow applicants to propose their own means of
compliance when the larger industry standard may be the appropriate level of safety for one, but
not all certification levels. Lastly, the FAA intends to continue to allow the use of the current
prescriptive means of compliance contained in current part 23 requirements as one obvious
alternative to showing compliance with proposed part 23. This would not apply to the proposed
sections that contain new requirements, such as §§ 23.200, 23.215, and 23.230.
The Part 23 Reorganization ARC also was aware the Administrator has accepted various
manufacturers’ internal standards in the past and recommended having that option stated in the
proposal. Proposed § 23.10 would allow applicants to submit their internal standards as means of
compliance for consideration by the Administrator.
iv. Removal of Subpart A Current Regulations
The FAA proposes removing current § 23.2, Special retroactive requirements, from part
23 because the operational rules currently address these requirements. The current retroactive
rule is more appropriate in the operating rules. The FAA proposes amending 14 CFR part 91, as
discussed later in the Discussion of the Proposed Regulatory Amendments to ensure removing
the current § 23.2 requirement would not affect the existing fleet.
2. Subpart B—Flight
a. General Discussion
The FAA proposes moving away from the current stall characteristics and spin testing
approach to address the largest cause of fatal accidents in small airplanes. Proposed § 23.215 in
subpart B would omit the one turn/three second spin requirement for normal category airplanes,
but it would increase the stall handling characteristics and stall warning requirements so the
53
airplane would be substantially more resistant to stall-based departures than the current rules
require.
The FAA also proposes eliminating the utility, acrobatic, and commuter categories in part
23. Accordingly, a new airplane would have to be approved for aerobatic loads as the normal
category, even if an applicant only wanted to spin the airplane. Therefore, the FAA proposes to
restrict certification of new airplanes for dual use, which can be done today using both the
normal and utility categories. The FAA believes that if the airplane can spin for spin training,
then the airplane can inadvertently stall and depart into a spin during normal operations. One of
the FAA’s goals is to prevent inadvertent stalls, so allowing airplanes that are commonly used as
rental airplanes to spin would defeat the goal. However, the FAA would consider accepting a
dual-purpose airplane if the airplane manufacturer provided a system that could be changed
mechanically or electronically from normal to aerobatic as a maintenance function rather than
controlled by the pilot.
The FAA proposes consolidating the performance requirements for high-speed
multiengine airplanes and multiengine airplanes that weigh over 12,500 pounds. These airplanes
are currently required to meet a series of one-engine-inoperative climb gradients. These climb
gradients were based on part 25 requirements and intended for commuter category airplanes used
in scheduled air service under parts 135 and 121. New airplanes certificated under part 23 are not
eligible for operation in scheduled service under part 121, diminishing the utility of the
commuter category for these airplanes.
More recently, part 23 multiengine jets intended to be used under parts 91 or 135 have
been certificated in the commuter category, using part 25 based climb gradient requirements. In
the spirit of the proposed rule change, the FAA has decided that the one-engine-inoperative
54
climb requirements would be independent of the number of engines and some of the original
requirements would be consolidated into a single requirement that would require performance
very close to what is required today. This action intends to maintain the performance capabilities
expected in 14 CFR part 135 operations.
The FAA proposes changes in the flight characteristics rules to keep the safety intent of
the existing requirements consistent with the other proposed part 23 sections. The current part 23
requirements are based on small airplanes, designed with reversible controls, which include some
accommodations for stability augmentation and autopilots. The FAA believes the proposed
language would capture the current requirements for flight characteristics and allows for varying
degrees of automated flight control systems in the future.
Finally, the FAA proposes adding a requirement to require certification levels 1 and 2
multiengine airplanes, not capable of climbing after a critical loss of thrust, to stall prior to
reaching the minimum directional control speed (VMC).
b. Specific Discussion of Changes
i. Proposed § 23.100, Weight and Center of Gravity
Proposed § 23.100 would require an applicant to determine weights and centers of gravity
that provide limits for the safe operation of the airplane. Additionally, it would require an
applicant to show compliance with each requirement of this subpart at each combination of
weight and center of gravity within the airplane’s range of loading conditions using tolerances
acceptable to the Administrator. Proposed § 23.100 would also require the condition of the
airplane at the time of determining its empty weight and center of gravity to be well defined and
easily repeatable.
55
Proposed § 23.100 would capture the safety intent of current §§ 23.21, Proof of
compliance; 23.23, Load distribution limits; 23.25, Weight limits; 23.29, Empty weight and
corresponding center of gravity; and 23.31, Removable ballast. This proposed section would
ensure an applicant considers the important weight and balance configurations that influence
performance, stability, and control when showing compliance with the flight requirements. The
main safety requirements of current §§ 23.21- 23.31 are located in current §§ 23.21 and 23.23.
Current § 23.21 allows for a range of loading conditions shown by test or systematic
investigation. The proposed rule would still allow for this flexibility, including the tolerances for
flight test. Sections 23.25-23.31 provide definitions and directions for determining weights and
centers of gravity and provides directions for informing the pilot. For these reasons, the
information in these sections is more appropriate as a means of compliance.
ii. Proposed § 23.105, Performance
Proposed § 23.105 would require an airplane to meet the performance requirements of
this subpart in various conditions based on the airplane’s certification and performance levels for
which certification is requested. Proposed § 23.105 also would require an applicant to develop
the performance data required by this subpart for various conditions, while also accounting for
losses due to atmospheric conditions, cooling needs, and other demands on power sources.
Finally, proposed § 23.105 would require the procedures used for determining takeoff and
landing distances to be executed consistently by pilots of average skill in atmospheric conditions
expected to be encountered in service.
Proposed § 23.105 would capture the safety intent of current § 23.45, Performance—
General. The safety intent of § 23.45(a) is captured in proposed § 23.105(a) and is essentially
56
unchanged from the current rule, except to incorporate the proposed certification levels and
speed divisions.
Proposed § 23.105(b) would capture the safety intent of § 23.45(b) by retaining
§ 23.45(b)(1) requirements and combining § 23.45(b)(2) and (b)(3) and allowing all airplanes to
use the cooling climb limits as their upper temperature. The level of safety remains the same as
the current part 23 because part 23 airplane pilots only have the limitations identified in the
airplane flight manual, including engine temperature limits.
Proposed § 23.105(c) would also capture the safety intent of § 23.45(f). The safety intent
of the current rule is to ensure an average pilot can consistently get the same results as published
in the Airplane Flight Manual (AFM). The FAA believes this requirement would ensure
applicants either perform their performance tests in a conservative manner or add margins and
procedures to the AFM performance section so an average pilot can achieve the same
performance.
Proposed § 23.105(d) would require performance data to account for losses due to
atmospheric conditions, cooling needs, and other demands. The current rule specifies the
position of cowl flaps or other means for controlling the engine air supply. The proposed
language accounts for airplane performance, if affected by the cooling needs of the propulsion
system, which is the safety intent of § 23.45, but would omit the details because they are more
appropriate as a means of compliance.
Proposed § 23.105(d) would also capture the safety intent § 23.45(d) and (e). The safety
intent of the current rule is to ensure the airplane performance accounts for minimum power
available from the propulsion system, considering atmospheric and cooling conditions and
accessories requiring power.
57
iii. Proposed § 23.110, Stall Speed
Proposed § 23.110 would require an applicant to determine the airplane stall speed or the
minimum steady flight speed for each flight configuration used in normal operations, accounting
for the most adverse conditions for each flight configuration, with power set at idle or zero
thrust.
Proposed § 23.110 would capture the safety intent of current § 23.49, Stalling speed. Stall
speeds are necessary to define operating and limiting speeds used to determine airplane
performance. They also provide a basis for determining kinetic energy in emergency landing
conditions. Therefore, determining stall speeds is required in the configurations used in the
operation of the airplane.
The FAA proposes removing the 61-knot stall speed division for single-engine airplanes
from the rules because this speed has not been a limitation since 1992 with the addition of the
options for stall speeds in excess of 61 knots in § 23.562, Emergency landing dynamic
conditions. Therefore, the 61-knot stall speed is a technical division rather than a limitation and
would be more appropriate as a means of compliance.
The FAA is changing its approach to crashworthiness. Instead of constraining the
connection between stall speed and crashworthiness to a single fixed speed, the FAA proposes
allowing alternative approaches to crashworthiness. The intent is to encourage incorporation of
innovations from other industries to provide more occupant protection in the airframe. This
approach would base occupant protection on the actual stall speed rather than a single mandated
stall speed.
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iv. Proposed § 23.115, Takeoff Performance
Proposed § 23.115 would require an applicant to determine airplane takeoff performance,
which includes the determination of ground roll and initial climb distance to 50 feet, accounting
for stall speed safety margins, minimum control speeds; and climb gradients. Proposed § 23.115
would also require the takeoff performance determination to include accelerate-stop, ground roll
and initial climb to 50 feet, and net takeoff flight path, after a sudden critical loss of thrust for
certification levels 1, 2, and 3 high-speed multiengine airplanes, multiengine airplanes with a
maximum takeoff weight greater than 12,500 pounds, and certification level 4 multiengine
airplanes.
Proposed § 23.115 would capture the safety intent of current §§ 23.51, Takeoff speeds;
and 23.61, Takeoff flight path. Takeoff distance information and the associated procedures for
achieving those distances are necessary for the safe operation of all airplanes certified under part
23. Proposed § 23.115 would require applicants to determine, develop, and publish distance and
procedure data for the pilot to use. The effects of airplane weight, field temperature and
elevation, winds, runway gradient, and runway surface also need to be available to the pilot
because they affect airplane performance. For proposed simple entry-level airplanes,
conservative analysis may supplement flight test while data for larger, higher performance
airplanes are expected to provide the level of precision that is accepted today.
Additionally, proposed § 23.115 would require applicants to determine critical thrust loss
cases for multiengine airplanes. Today, the loss of one engine on a two-engine airplane is the
standard model. The future possibilities for the functions of engines, if different from thrust, and
how the engines are controlled, may determine critical thrust loss. For example, a large number
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of engines along the leading edge of a wing could function as a high-lift device as well as
provide thrust.
Historically, limited propulsion options and the need for inherent stability from
reversible, mechanical control systems have restrained airplane configurations. The FAA
anticipates that new propulsion systems and affordable electronic flight control systems will
challenge these traditional designs and need alternative means of compliance. Speed multiples
and factors used in current part 23 prescriptive requirements are based on traditional airplane
configurations. Part 23 mandates these details of design for compliance. The FAA believes
removing these details would provide applicants with the agility and flexibility to address these
new airplane configurations. The current factors will still apply for traditional configurations, but
proposed performance-based requirements should allow rapid adoption of new means of
compliance for future airplane configurations.
The FAA proposes removing airplane categories and weight and propulsion certification
divisions for multiengine jets over 6,000 pounds and replacing them with divisions based on risk
and performance. The commuter category, originally intended for the certification of airplanes
over 12,500 pounds and up to 19 passengers, is currently used for larger business jets with less
than ten passengers. The FAA proposes that high-speed, multiengine and multiengine airplanes
over 12,500 pounds should continue meeting the equivalent commuter category performancebased requirements. The historical assumption applied to jets was that they were fast, had high
wing loadings, and used significant runway distances for takeoff and landing. Therefore, all jets
were required to have guaranteed climb performance with one engine inoperative. This
requirement does not currently apply to single engine jets. The proposed performance
requirements would be based on number of passengers (certification level) and airplane
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performance (performance level), not weight or propulsion type. The proposed certification and
performance levels approach would not offer a one-to-one relationship with the current
requirements. A low-speed turbine-powered airplane may be more appropriately addressed by
regulations currently applicable to piston-powered airplanes, while a piston-powered or a highspeed electric airplane may be more appropriately addressed by regulations currently used for the
certification of turbine-powered airplanes. The proposed certification and performance level
approach, while different from the current divisions, would capture the safety intent of part 23
more appropriately than the current propulsion and weight divisions.
v. Proposed § 23.120, Climb Requirements
Proposed § 23.120 would require an applicant to demonstrate various minimum climb
performances out of ground effect, depending on the airplane’s certification level, engines, and
performance capability. This new provision would capture the safety intent of current §§ 23.65,
Climb: All engines operating; 23.67, Climb: One engine inoperative; and 23.77, Balked landing.
Minimum climb performance information is necessary so pilots can determine if they have
adequate clearance from obstacles beyond the end of the runway. New engine technologies,
especially electric, would allow for alternative configurations that would invalidate many of the
detailed test configuration and power assumptions that are in the current requirements.
Part 23 currently has a large matrix for all the climb requirements that includes category,
weight, and number of engines, resulting in over 20 different climb gradient requirements. This
reflects the growth in the variety of different airplane types that has occurred since the
certification regulations were first adopted in CAR 3. Because the FAA proposes simplifying
these divisions using certification levels and airplane performance levels, it can eliminate
required climb gradients for three and four engines. The FAA proposes basing multiengine climb
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gradients on critical loss for thrust and using the gradient for the current twin-engine airplanes
because it has resulted in a safe service history. The FAA proposes replacing the term “failure of
the critical engine” (which addresses a twin engine airplane) with “critical loss of thrust” for
airplanes certificated under those provisions. The reason for replacing this term is that with
configurations utilizing large numbers of engines, the failure modes may not follow the
traditional failure modes as with the loss of one engine on a two-engine airplane. Furthermore,
the FAA proposes retaining and consolidating the climb gradients from current § 23.67 because
these gradients are important minimum performance requirements for maintaining the current
level of safety.
Proposed § 23.120(a) would capture the safety intent of current § 23.65. It would retain
the existing climb gradients and atmospheric conditions required for pilot planning.
Proposed § 23.120(b) would capture the safety intent of current § 23.67, and consolidates
the weight and propulsion divisions into all engines operating, critical loss of thrust, and balked
landing groups. Furthermore, for high-speed airplanes, after a critical loss of thrust, the FAA
proposes reducing the number of required climb conditions for certification to one gradient at
400 feet (122 meters) above the takeoff surface. For the typical part 23 certified twin-engine
airplane, the required climb gradient at 400 feet (122 meters) above the takeoff surface is
generally the most challenging. Airplanes that have the performance to meet this one
requirement typically can meet all the current requirements. For certification levels 3 and 4,
high-speed multiengine airplanes, the FAA proposes consolidating the configurations currently
prescribed for the second segment climb and a discontinued approach. The climb gradient
difference between these segments is 0.1 percent and uses the takeoff flap configuration rather
than the approach flap configuration. Requiring only one climb gradient at 400 feet (122 meters)
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above the takeoff surface with the landing gear retracted and flaps in the approach position
would maintain the current level of safety while reducing the requirements by eliminating initial,
final, and discontinued approach climb tests. Because the proposed requirements would reduce
the amount of climb testing for designs intended for use under part 91, applicants would also
need to provide the traditional operational performance data, as is currently done, if the design is
intended to be used for commercial operations under part 135 operating rules.
The FAA also proposes to normalize the initial climb height to 50 feet (15 meters) above
the takeoff surface. The regulations for the certification of commuter category airplanes
essentially adopted many of the part 25 climb requirements, including an initial climb height of
35 feet (11 meters) above the takeoff surface. When the commuter category was adopted, the
expectation was that these airplanes would be used in part 121 service. This expectation allowed
the FAA to accept the part 25 assumption that takeoff distances would be factored; thus,
providing a safety margin to offset the lower initial climb height. Part 23 requirements provide
minimum safe operations for part 91, which does not require factored takeoff distances.
Therefore, allowing a 35 foot (11 meters) height above the takeoff surface is a lower safety
margin than used for smaller airplanes and, for this reason, the FAA proposes to make all
airplanes certificated under part 23 use 50 feet (15 meters) above the takeoff surface.
vi. Proposed § 23.125, Climb Information
Proposed § 23.125 would require an applicant to determine the climb performance for—
 All single engine airplanes;
 Certification level 3 multiengine airplanes after a critical loss of thrust on takeoff
in the initial climb configuration; and
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 All multiengine airplanes during the enroute phase of flight with all engines
operating and after a critical loss of thrust in the cruise configuration.
Proposed § 23.125 would also require an applicant to determine the glide performance of
the airplane after a complete loss of thrust for single engine airplanes.
Proposed § 23.125 would capture the safety intent of current §§ 23.63, Climb: General;
23.66, Takeoff climb: One-engine inoperative; 23.69, Enroute climb/descent; and 23.71, Glide:
Single-engine airplanes. The intent of these requirements is to provide pilots with climb and
glide performance data that is important for safety, especially in conditions near the performance
limits of the airplane. Sections 23.63, 23.66, and 23.69 are not minimum performance sections,
but contain information used in the development of the AFM. Proposed § 23.125 would require
an applicant to determine climb performance. The performance data determination provides a
good example of how the use of certification levels can allow simplified approaches to meet
applicable airworthiness requirements for simple, and levels 1 and 2 airplanes.
vii. Proposed § 23.130, Landing
Proposed § 23.130 would require an applicant to determine the landing distance for
standard temperatures at each weight and altitude within the operational limits for landing. The
landing distance determination would start from a height of 50 feet (15 meters) above the landing
surface, require the airplane to land and come to a stop (or for water operations, reach a speed of
3 knots) using approach and landing speeds, configurations, and procedures, which allow a pilot
of average skill to meet the landing distance consistently and without causing damage or injury.
Proposed § 23.130 would require these determinations for standard temperatures at each weight
and altitude within the operational limits for landing.
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Proposed § 23.130 would capture the safety intent of current § 23.73, Reference landing
approach speed, and § 23.75, Landing Distance. Landing distance information and the associated
procedures for achieving those distances are necessary to prevent runway overruns. Applicants
would be required to determine, develop, and publish distance and procedures data for use in
pilot planning. Proposed § 23.130 would combine the current requirements to determine
approach speed and landing distance because a determination of both is required for a landing
distance determination.
viii. Proposed § 23.200, Controllability
Proposed § 23.200 would require the airplane to be controllable and maneuverable,
without requiring exceptional piloting skill, alertness, or strength, within the operating envelope,
at all loading conditions for which certification is requested. This would would include during
low-speed operations, including stalls, with any probable flight control or propulsion system
failure, and during configuration changes. Proposed § 23.200 would require the airplane to be
able to complete a landing without causing damage or serious injury, in the landing configuration
at a speed of VREF minus 5 knots using the approach gradient equal to the steepest used in the
landing distance determination. Proposed § 23.200 would require VMC not to exceed VS1 or VS0
for all practical weights and configurations within the operating envelope of the airplane for
certification levels 1 and 2 multiengine airplanes that cannot climb after a critical loss of thrust.
Proposed § 23.200 would also require an applicant to demonstrate those aerobatic maneuvers for
which certification is requested and determine entry speeds.
Proposed § 23.200 would capture the safety intent of §§ 23.141, Flight Characteristics—
General, 23.143, Controllability and Maneuverability—General; 23.145, Longitudinal control;
23.147 Directional and lateral control; 23.149, Minimum control speed; 23.151, Acrobatic
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maneuvers; 23.153, Control during landing; 23.155, Elevator control force in maneuvers; 23.157,
Rate of roll; 23.697(b) and (c), Wing flap controls. Proposed § 23.200 would ensure the
maneuvering flight characteristics of the airplane are safe and predictable throughout the flight
envelope and result in repeatable, smooth transitions between turns, climbs, descents, and level
flight. Configuration changes, such as flap extension and retraction, landing gear extension and
retraction, and spoiler extension and retraction, along with probable failures resulting in
asymmetric thrust, would also have to result in safe, controllable, and predictable characteristics.
Proposed § 23.200(a) and (b) would capture the safety intent of §§ 23.143, Controllability
and Maneuverability—General; 23.145, Longitudinal control; 23.147, Directional and lateral
control; 23.149, Minimum control speed; 23.151, Acrobatic maneuvers; 23.153, Control during
landings; 23.155, Elevator control force in maneuvers; and 23.157, Rate of roll. The FAA
proposes limiting the requirements for practical loadings and operating altitudes without the use
of exceptional piloting skill, alertness, or strength.
Current part 23 provides prescriptive and detailed test requirements based on specific
airplane configurations. Additionally, the current rules include flight test procedures that are
based on traditional reversible controls and engine locations that are, in some cases, derived from
airplanes designed in the 1930’s. The FAA proposes performance-based requirements that would
remain applicable to traditionally designed airplanes, but allow alternative approaches to
showing compliance based on new configurations, flight control systems, engine locations, and
number of engines.
Proposed § 23.200(c) would require all certification levels 1 and 2 multiengine airplanes
that lack the performance to climb after a critical loss of thrust to stall before loss of directional
control. This is a new requirement and it targets the high number of fatal accidents that occur
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after an engine failure in this class of airplane. Light multiengine airplanes that lack the
performance to climb after the critical loss of thrust are especially susceptible to this type of
accident. The Part 23 Reorganization ARC discussed and several members proposed that all
multiengine airplanes have guaranteed climb performance after a critical loss of thrust.
Ultimately, this approach was rejected, as it could impose a significant cost on the production of
training airplanes. Furthermore, several members pointed out that the safety concern was not that
the airplane could not climb on one engine, but rather that the airplane would depart controlled
flight at low speeds above stall as a result of asymmetric thrust. The FAA agrees that loss of
control caused by asymmetric thrust is the critical safety issue that should be addressed and the
FAA believes that the proposed rule responds to this concern.
The FAA recognizes concerns regarding the proposed requirement—if the airplane is
allowed to stall, the asymmetric thrust will still cause the airplane to lose directional control and
likely depart controlled flight. The FAA agrees, but believes that pilots are typically more aware
of their stall speeds than minimum control speed, especially during turns. Furthermore, these
airplanes would be required to meet the proposed stall warning and stall characteristic
requirements, which the FAA expects would provide additional safety margins beyond current
requirements. Finally, the system that provides stall warning could also be designed to provide
VMC warning.
ix. Proposed § 23.205, Trim
Proposed § 23.205 would require the airplane to maintain longitudinal, lateral, and
directional trim under various conditions, depending on the airplane’s certification level, without
allowing residual forces to fatigue or distract the pilot during likely emergency operations,
including a critical loss of thrust on multiengine airplanes.
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Proposed § 23.205 would capture the safety intent of current § 23.161, Trim.
Section 23.161(a) addresses the safety intent while paragraphs (b), (c), (d), and (e) provide
prescriptive details on how to do flight testing for traditionally configured airplanes and are more
appropriate for inclusion in means of compliance.
x. Proposed § 23.210, Stability
Proposed § 23.210 would require airplanes not certified for aerobatics to have static and
dynamic longitudinal, lateral, and directional stability in normal operations, and provide stable
control force feedback throughout the operating envelope. Proposed § 23.210 would also
preclude any airplane from exhibiting any divergent stability characteristic so unstable as to
increase the pilot’s workload or otherwise endanger the airplane and its occupants.
Proposed § 23.210 would capture the safety intent of the current §§ 23.171, Stability—
General; 23.173, Static longitudinal stability; 23.175, demonstration of static longitudinal
stability; 23.177, Static directional and lateral stability; 23.179, Instrumented stick force
measurements; and 23.181, Dynamic stability. The current requirements have their origins in
Aeronautics Bulletin 7, amendment 7a, effective October 1, 1934, which predates CAR 3. These
airplane handling quality and stability requirements were based on the technology associated
with simple mechanical control systems and what was considered acceptable on existing
airplanes of the time. Although many of these requirements are still appropriate for traditional
flight control systems, they do not take into account the capabilities of new computer-based
flight control systems. The FAA recognizes the availability of hybrid reversible and automated
flight control systems and proposes performance-based language that would allow their
installation in part 23 certificated airplanes without the use of special conditions, while still
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maintaining adequate requirements for reversible controls. The intent is to facilitate the use of
systems that may enhance safety while reducing pilot workload.
xi. Proposed § 23.215, Stall Characteristics, Stall Warning, and Spins
Proposed § 23.215 would require an airplane to have controllable stall characteristics in
straight flight, turning flight, and accelerated turning flight with a clear and distinctive stall
warning that would provide sufficient margin to prevent inadvertent stalling. Proposed § 23.215
would allow for alternative approaches to meeting this requirement for certification levels 1 and
2 airplanes and certification level 3 single-engine airplanes, not certified for aerobatics, in order
to avoid a tendency to inadvertently depart controlled flight. Proposed § 23.215 would require
airplanes certified for aerobatics to have controllable stall characteristics and the ability to
recover within one and one-half additional turns after initiation of the first control action from
any point in a spin. Additionally, the airplane would not be allowed to exceed six turns or any
greater number of turns for which certification is requested while remaining within the operating
limitations of the airplane. Proposed § 23.215 would preclude airplanes certified for aerobatics
from having spin characteristics that would result in unrecoverable spins due to pilot
disorientation or incapacitation or any use of the flight or engine power controls.
Proposed § 23.215 would capture the safety intent of current §§ 23.201, Wings level stall;
23.203, Turning flight and accelerated turning stalls; 23.207, Stall warning; and 23.221,
Spinning. Historically, the FAA focused its requirements on the ability of the airplane to recover
from a one-turn or three-second spin more than on the stall characteristics of the airplane. From
the first fatal stall accident in the Wright Flyer airplane to today’s fatal stall accidents, the
number one cause in small airplanes is a departure from controlled flight following an
inadvertent stall.
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Except for accidental departures from controlled flight during stall training, most of these
inadvertent departures occur in close proximity to the ground, and because of this, the current
requirement to recover from a one-turn or three-second spin may not be the best method to assess
the safety of the airplane. Even an experienced pilot may not have enough altitude to recover
from the spin before impacting the ground. For this reason, the FAA proposes to delete the oneturn/three-second spin recovery requirement for normal category airplanes. Instead, the FAA
proposes to increase the stall characteristics requirements by requiring that all certification levels
1 and 2 airplanes and certification level 3 single-engine airplanes provide substantial departure
resistance to prevent inadvertent stalls from resulting in a departure from controlled flight and
becoming fatal accidents.
Accident studies show that even hitting the ground as a result of a stall can be survivable
if the airplane is still in controlled flight. Conversely, impacting the ground out of control is
typically fatal. The FAA envisions numerous alternative approaches to meeting the proposed
requirements, ranging from one extreme of spin resistance to the other extreme of a total
systems-based approach such as stick pusher. Furthermore, there are envelope protection systems
and stall warning concepts that could also be considered when assessing departure resistance.
The possible approaches to meeting the proposed requirements are so broad that these
alternatives would be better addressed in means of compliance. This level of protection may vary
based on the characteristics of the airplane, but the FAA expects this change in design
philosophy would increase the level of protection designed into airplanes under this proposed
rule. Certification level 3 multiengine airplanes and certification level 4 airplanes historically
have not had a large number of departure-related accidents. While the FAA encourages
manufacturers to consider designing departure resistance into these airplanes, the FAA does not
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propose adding a new requirement for certification level 3 multiengine airplanes and certification
level 4 airplanes.
The FAA also proposes revising stall warning requirements by removing prescriptive
speed based stall warning requirements and requiring a clear and distinctive warning with
sufficient warning margin for the pilot to prevent a stall. Historically, stall warning systems in
part 23 airplanes have been simple, mechanical vanes that may or may not provide reasonable
lead-time to prevent a stall. These systems also can provide false alerts when they are not
needed, creating a nuisance. Furthermore, similar sounding warning horns that alert the pilot of
other situations can result in the pilot either becoming used to the warning sounds or mistaking
the stall warning for another warning such as the autopilot disconnect horn. The FAA believes
removing the current prescriptive speed based stall warning from the rules would encourage the
installation of better, more effective low speed awareness systems that may use angle of attack, a
speed decay rate, or clear voice commands to alert the pilot.
xii. Proposed § 23.220, Ground and Water Handling Characteristics
Proposed § 23.220 would require airplanes intended for operation on land or water to
have controllable longitudinal, and directional handling characteristics during taxi, takeoff, and
landing operations. Proposed § 23.220 would also require an applicant to establish a maximum
wave height shown to provide for controllable longitudinal, and directional handling
characteristics and any necessary water handling procedures for those airplanes intended for
operation on water.
Proposed § 23.220 would capture the safety intent of §§ 23.231, Longitudinal stability
and control; 23.233, Directional stability and control; 23.235, Operation on unpaved surfaces;
23.237, Operation on water; and 23.239, Spray characteristics.
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xiii. Proposed § 23.225, Vibration, Buffeting, And High-Speed Characteristics
Proposed § 23.225 would preclude vibration and buffeting from interfering with the
control of the airplane or causing fatigue to the flightcrew, for operations up to VD/MD. Proposed
§ 23.225 would allow stall warning buffet within these limits. Proposed § 23.225 would preclude
perceptible buffeting in cruise configuration at 1g and at any speed up to VMO/MMO, except stall
buffeting for high-speed airplanes and all airplanes with a maximum operating altitude greater
than 25,000 feet (7,620 meters) pressure altitude. Proposed § 23.225 would require an applicant
seeking certification of a high-speed airplane to determine the positive maneuvering load factors
at which the onset of perceptible buffet occurs in the cruise configuration within the operational
envelope and preclude likely inadvertent excursions beyond this boundary from resulting in
structural damage. Proposed § 23.225 would also require high-speed airplanes to have recovery
characteristics that do not result in structural damage or loss of control, beginning at any likely
speed up to VMO/MMO, following an inadvertent speed increase and a high-speed trim upset.
Proposed § 23.225 would capture the safety intent of current §§ 23.251, Vibration and
buffeting; 23.253, High speed characteristics; and 23.255, Out of trim characteristics. Proposed
§ 23.225(a), (b), and (c) would capture the safety of current § 23.251(a), (b), and(c). The current
safety intent of §§ 23.253 and 23.255 are incorporated in proposed § 23.225(d).
Proposed § 23.225(d)(1) addresses the current language in § 23.253, which indirectly
divides the airplanes by engine type rather than performance. These requirements have typically
been applied automatically to turbine-powered airplanes with the assumption that all turbinepowered airplanes flew fast and high. Piston or electric airplanes were not required to meet these
requirements even if they were faster than many turboprops, because of propulsion assumptions
in the past. For this reason, the FAA is amending this requirement to be based on performance
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instead of propulsion type using the same high-speed criteria from other subpart B sections. The
existing details would be removed from the rules, as they are more appropriate as means of
compliance because it would allow for alternatives for non-traditional airplanes, such as very fast
piston airplanes.
Proposed § 23.225(d)(2) would address the current safety intent in § 23.255 by relying on
performance and design characteristics without discriminating based on propulsion type. The
specific design details are more appropriate as means of compliance.
xiv. Proposed § 23.230, Performance and Flight Characteristics Requirements for Flight In
Icing Conditions
Proposed § 23.230 would require an applicant requesting certification for flight in icing
conditions to demonstrate compliance with each requirement of this subpart. Exceptions to this
rule would be those applicable to spins and any requirement that would have to be demonstrated
at speeds in excess of 250 KCAS, VMO or MMO, or a speed that an applicant demonstrates the
airframe would be free of ice accretion. Proposed § 23.230 would require the stall warning for
flight in icing conditions and non-icing conditions to be the same. Proposed § 23.230 would
require an applicant requesting certification for flight in icing conditions to provide a means to
detect any icing conditions for which certification is not requested and demonstrate the airplane’s
ability to avoid or exit those conditions. Proposed § 23.230 would also require an applicant to
develop an operating limitation to prohibit intentional flight, including takeoff and landing, into
icing conditions for which the airplane is not certified to operate. Proposed § 23.230 would also
increase safety by adding optional icing conditions a manufacturer may demonstrate its airplane
can either safely operate in, detect and safely exit, or avoid. Proposed § 23.230 would only apply
to applicants seeking certification for flight in icing.
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Proposed § 23.230 would capture the safety intent of the performance and flight
characteristics requirements in current § 23.1419(a) and along with proposed §§ 23.940,
Powerplant ice protection, and 23.1405, Flight in icing conditions, and their respective means of
compliance would address NTSB safety recommendations A-96-54 and A-96-56.
Section 23.1419 specifies that airplanes must be able to operate safely in the icing conditions
identified in appendix C to part 25, which encompass cloud size drops of less than 100 microns
in diameter. Freezing drizzle (i.e., drops up to 500 microns in diameter) and freezing rain (i.e.,
drops greater than 500 microns in diameter) icing conditions, which can result in ice accretion aft
of leading edge ice protection systems, are not included in appendix C to part 25. Amendment
25-140 (79 FR 65507, November 4, 2014) added these icing conditions to appendix O to part 25
and are not being defined in proposed § 23.230. The FAA believes that the definitions of these
optional icing conditions would be more appropriate as a means of compliance. The standards
for “capable of operating safely” in these conditions would be the same as cloud icing with
additional icing conditions in the takeoff phase.
If certification for flight in the optional freezing drizzle or freezing rain conditions is not
sought, proposed § 23.230 would require these conditions be avoided or detected and exited
safely. The means of compliance for the latter, detect and exit the situation, would be similar to
current guidance in AC 23.1419-2D, Certification of Part 23 Airplanes for Flight in Icing
Conditions, and is currently applied during part 23 airplane icing certifications. These criteria are
not as extensive as recommended by the Part 23 Icing ARC, but the FAA did not want to impose
an additional burden on industry because the service history of airplanes certified under part 23
and the latest icing regulations at amendment 23-43 (58 FR 18958, April 9, 1993) show no SLD
related accidents. The FAA believes the safety of the existing fleet can be greatly increased by
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improving the freezing drizzle and freezing rain capability of automated surface weather
observation systems and pilot education and training of the limits of icing certification.
Proposed § 23.230(b) would provide an option to avoid, in lieu of detecting and exiting,
the freezing drizzle or freezing rain icing conditions for which the airplane is not certified. This
option is not in current guidance and such technology currently does not exist. The rule would
provide an option in the event the technology is developed. The FAA believes avoiding rather
than detecting and exiting would provide for safer airplane operations and reduce certification
costs.
Proposed § 23.230(c) would require an AFM limitation to prohibit flight in icing
conditions for which the airplane is not certified. This reflects current guidance in AC 23.14192D, which most manufacturers of new part 23 icing certified airplanes follow today. A minority
of new manufacturers are not using AC 23.1419-2D guidance and have inserted AFM limitation
language that reflects Airworthiness Directives (AD) that were issued globally to pneumatic
boot-equipped airplanes between 1996 and 1998. The ADs in the below table require immediate
exit from severe icing and warn that freezing drizzle and freezing rain may be conducive to
severe icing. The proposed new limitation is intended to prohibit flight in known icing
conditions, not forecast conditions.
Airplane Model
Aerostar Aircraft Corporation Models PA-60-600, PA-60-601, PA-60-601P,
PA-60-602P, and PA-60-700P Airplanes.
Pilatus Britten-Norman Ltd., Models BN-2A, BN-2B, and BN-2T Airplanes.
Pilatus Aircraft Ltd., Models PC-12 and PC-12/45 Airplanes.
Partenavia Costruzioni Aeronauticas, S.p.A. Model P68, AP68TP 300, AP68TP
600 Airplanes.
Mitsubishi Heavy Industries, Ltd., MU-2B Series Airplanes.
Harbin Aircraft Manufacturing Corp., Model Y12 IV airplanes.
Empresa Brasileira de Aeronautica S.A. Airplanes. (Embraer) Models EMB110P1 and EMB-110P2 Airplanes.
Dornier Luftfahrt GmbH, 228 Series Airplanes.
De Havilland, Inc., DHC-6 Series Airplanes.
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Docket
Final Rule
97-CE-56-AD
98-04-23
97-CE-54-AD
97-CE-53-AD
98-04-21
98-20-28
97-CE-51-AD
98-04-20
96-CE-61-AD
97-CE-50-AD
96-25-02
98-04-19
96-CE-02-AD
96-09-12
96-CE-04-AD
96-CE-01-AD
96-09-14
96-09-11
Airplane Model
The Cessna Aircraft Company, 208 Series.
The Cessna Aircraft Company, Model T210R airplane.
The Cessna Aircraft Company, Models T210, P210, P210R airplanes.
The Cessna Aircraft Company Models T303, 310R, T310R, 335, 340A, 402B,
402C, 404, F406, 414, 414A, 421B, 421C, 425, and 441 Airplanes.
Jetstream Aircraft Limited Models 3101 and 3201 Airplanes.
The New Piper Aircraft PA-23, PA-30, PA-31, PA-34, PA-39, PA-40, and PA42 Series Airplanes.
The New Piper Aircraft Corporation Models PA-46-310P and PA-46-350P
Airplanes.
Beech Aircraft Corporation Models 99, 99A, A99A, B99, C99, B200, B200C,
1900, 1900C, and 1900D Airplanes.
Raytheon Aircraft Company 200 Series Airplanes.
Raytheon Aircraft Company Models E55, E55A, 58, 58A, 58P, 58PA, 58TC,
58TCA Airplanes, and 60, 65-B80, 65-B90, 90, F90, 100, 300, and B300 Series
Airplanes.
Raytheon Aircraft Company Model 2000 Airplanes.
AeroSpace Technologies Of Australia Pty Ltd., Models N22B and N24A.
SIAI Marchetti, S.r.1 Models SF600 and SF600A Airplanes.
SOCATA--Groupe AEROSPATIALE, Model TBM 700 Airplanes.
Twin Commander Aircraft Corporation Models 500, 500-A, 500-B, 500-S, 500U, 520, 560, 560-A, 560-E, 560-F, 680, 680-E, 680FL(P), 680T, 680V, 680W,
681, 685, 690, 690A, 690B, 690C, 690D, 695, 695A, 695B, and 720 Airplanes.
Fairchild Aircraft Corporation, SA226 and SA227 Series Airplanes.
Docket
96-CE-05-AD
98-CE-19-AD
97-CE-62-AD
Final Rule
96-09-15
98-20-33
98-05-14 R1
97-CE-63-AD
98-04-28
96-CE-07-AD
96-09-17
98-CE-77-AD
99-14-01
97-CE-60-AD
98-04-26
96-CE-03-AD
96-09-13
98-CE-17-AD
98-20-38
97-CE-58-AD
98-04-24
97-CE-59-AD
97-CE-49-AD
97-CE-64-AD
97-CE-55-AD
98-04-25
98-04-18
98-05-15
98-04-22
97-CE-57-AD
98-20-34
96-CE-06-AD
96-09-16
Recently, manufacturers of airplanes certificated under part 23 have proposed inhibiting,
or optimizing, bleed air ice protection systems above an altitude of 30,000 feet (9,144 meters)
because the icing conditions defined in the appendix C to part 25 are limited to below this
altitude. The FAA believes ice protection design at high altitude should be addressed as a means
of compliance and not in the proposed rule due to various acceptable design solutions. An
industry means of compliance would negate the need for a special condition or means of
compliance issue paper currently required for these projects.
xv. Current Subpart B Regulations Relocated to Other Proposed Subparts
The FAA proposes addressing the safety intent of § 23.33, Propeller speed and pitch
limits, in § 23.900(a) of the propulsion rules. Additionally, the first part of the current
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§ 23.251(a) that addresses structural damage has been relocated and is now addressed under
“flutter” in proposed subpart C to part 23.
The FAA proposes adopting the Part 23 Icing and Part 23 Reorganization ARC’s
recommendations to move performance and flight characteristics requirements in icing, currently
in § 23.1419, to subpart B, so that proposed § 23.1405 only contains systems requirements.
Proposed § 23.230(a) would also include stall warning requirements. Current guidance contains
these stall warning recommendations (i.e., margin and type of stall) and service history shows
them to be necessary for safe flight in icing conditions. The exceptions for spin and high-speed
requirements are consistent with the current rule and industry practice that have shown to
provide an adequate level of safety in icing conditions. The FAA determined that the evaluations
of ice contaminated tailplane stall susceptibility, lateral control in icing, and autopilot operation
in icing, which are included in current guidance for part 23 icing certification, are more
appropriately addressed as a means of compliance.
xvi. Removal of Subpart B Current Regulations
The FAA proposes removing § 23.45(g) that requires takeoff and landing distances be
determined on a smooth, dry, hard-surfaced runway. The FAA believes that most performance
tests would be done on smooth, dry, hard-surfaced runways because these surfaces provide
applicants with the best results. Performance determinations on surfaces other than smooth, dry
hard surfaces would provide conservative results and be acceptable as long as the surface was
specified in the AFM. Therefore, the FAA believes retaining this requirement is unnecessary.
The FAA proposes removing § 23.63, Climb: General, which addresses the general climb
requirements, because the safety intent contained in this section is redundant with the safety
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intent proposed in § 23.125 and the testing procedures contained in § 23.63 are more appropriate
for inclusion in means of compliance.
The FAA proposes removing current § 23.221(a) and (b), which address spinning
requirements for normal and utility category airplanes, and would no longer be necessary. The
increased focus on preventing stall-based departures along with improved stall margin awareness
would provide a level of safety higher than would be achieved through spin testing.
The FAA proposes removing the reference to appendix C to part 25, part II, currently in
§ 23.1419, Ice protection, paragraph (a), when relocating § 23.1419 to proposed § 23.230 and
23.1405. Part II is a means of compliance for determining critical ice accretions on transport
category airplanes and is not applicable to airplanes certified under part 23.
3. Subpart C—Structures
a. General Discussion
The FAA’s intent in proposed subpart C is to provide a regulatory framework that
maintains the current level of safety while 1) allowing for certification of unique airplane
configurations with new technology and materials, and 2) supporting new means of compliance,
testing, and analysis. To support new technologies, the FAA proposes to incorporate the safety
intent of recent special conditions for airplanes equipped with systems that affect structural
performance, such as load alleviation systems, in proposed § 23.305. To support new means of
compliance, the FAA proposes in § 23.600 to emphasize a holistic approach to occupant safety,
which would allow certain applicants to omit current required dynamic seat testing.
It is not the FAA’s intent to reduce the level of safety in the proposed subpart C. The
FAA based the prescriptive requirements in current subparts C and D on service history, historic
test data, and lessons learned. These requirements have provided a level of safety where
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structural failure is rare and most often attributable to airplane upset or pilot disorientation in
instrument meteorological conditions. A means of compliance to proposed subpart C must
maintain the level of safety provided by the current regulations. Applicants would need to
substantiate the level of safety for proposed means of compliance that deviate from the
prescriptive regulations.
Proposed subpart C would replace current subpart C and include those sections of current
subpart D that are applicable to the airframe. We have arranged proposed subpart C into the
following five topics:

General: including § 23.300, Structural design envelope; and § 23.305 Interaction
of systems and structures.

Structural Loads: including § 23.310, Structural design loads; § 23.315, Flight
load conditions; § 23.320, Ground and water load conditions; § 23.325,
Component loading conditions; and § 23.330, Limit and ultimate loads.

Structural performance: including § 23.400, Structural strength; § 23.405,
Structural durability; and § 23.410, Aeroelasticity.

Design: including § 23.500, Structural design; § 23.505, Protection of structure;
§ 23.510, Materials and processes; and § 23.515, Special factors of safety.

Structural occupant protection: included in § 23.600, Emergency conditions.
The FAA proposes removing the content of current appendix A to part 23, Simplified
design load criteria; appendix C to part 23, Basic landing conditions; appendix D to part 23,
Wheel spin-up and spring-back loads; and appendix I to part 23, Seaplane loads. The content of
these current part 23 appendices is more appropriate for inclusion in means of compliance. The
FAA also proposes removing appendix B to part 23, Reserved, since the content of this appendix
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was removed at amendment 23-42 (56 FR 344, January 3, 1991). Refer to appendix 1 of this
preamble for a cross-reference table detailing how the current regulations are addressed in the
proposed part 23 regulations.
b. Specific Discussion of Changes
i. Proposed § 23.300, Structural Design Envelope
Proposed § 23.300 would require an applicant to determine the structural design
envelope, which describes the range and limits of airplane design and operational parameters for
which an applicant would show compliance with the requirements of this subpart. Proposed
§ 23.300 would capture the safety intent of current §§ 23.321, Loads—General, paragraphs (b)
and (c); 23.333, Flight envelope, paragraphs (a), (b), and (d); 23.335, Design airspeeds; 23.337,
Limit maneuvering load factors, paragraphs (a) and (b); and 23.343, Design fuel loads,
paragraphs (a) and (b).
Proposed § 23.300 would require the applicant to determine and document the range of
airplane and operational parameters for which the applicant will show compliance with the
requirements of subpart C. These parameters would include the design airspeeds and maneuver
load factors often depicted as a V-n diagram. An applicant would be required to determine
design airspeeds, including the design maneuvering speed (VA), the design cruising speed (VC),
the design dive speed (VD), design flap and landing gear speeds, and any other speed used as a
design limitation. For certification of level 4 airplanes, an applicant would be required to
determine a rough air penetration speed, VB.
Additionally, applicants would have to determine the design maneuver load factors based
on the intended usage of the airplane and the values associated with the level of safety
experienced with current designs. Applicants have rarely used the relief for maneuvering load
80
factors based on airplane capabilities in current § 23.337(c). The FAA views this relief as an
application of physical principles, and believes that this current requirement does not need to be
addressed in proposed § 23.300.
Design weights and inertia parameters are also part of the structural design envelope.
Design weights include the empty weight, maximum weight, takeoff and landing weight, and
maximum zero fuel weight. The range of center of gravity locations at these and other weights is
depicted as the weight center of gravity envelope. An applicant would have to determine the
weight and center of gravity of occupants, payload, and fuel as well as any mass moments of
inertia required for loads or flutter analysis. An applicant would also have to specify any other
parameters that describe the structural design envelope. These parameters include maximum
altitude limitations, Mach number limitations, and control surface deflections.
ii. Proposed § 23.305, Interaction of Systems and Structures
Proposed § 23.305 would provide a regulatory framework for the evaluation of systems
intended to modify an airplane’s structural design envelope or structural performance and other
systems whose normal operating state or failed states may affect structural performance.
Compliance with proposed § 23.305 would provide acceptable mitigation of structural hazards
identified in the functional hazard assessments required by proposed § 23.1315.
Proposed § 23.305 would apply to airplanes equipped with—

Structural systems, including load alleviation systems, where the intended
function is to modify structural performance, to alleviate the impact of subpart C
requirements, or provide a means of compliance to subpart C requirements; and

Systems where the intended function is non-structural, but whose normal
operation or failure states affect the structural design envelope or structural
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performance, and would include fuel management systems, flight-envelope
protection systems, and active control systems.
Under the current regulations, an applicant seeking certification of airplanes
incorporating structural and non-structural systems must ensure that failures of these systems
will not result in exceeding the structural design envelope or the structural design loads, or other
structural performance characteristics. An applicant has the option of designing the structure to
the full subpart C and subpart D requirements, including margins of safety, with the system in its
failed state. This option may result in increased structural weight and reduced airplane
performance and utility.
Proposed § 23.1315 in subpart F would apply to both structural and non-structural
systems. Guidance material for current § 23.1309, the corresponding regulation to proposed
§ 23.1315, allows for different acceptable values for likelihood of failures based on the severity
of the hazard, airplane weight, and method of propulsion. These different values encourage the
incorporation of equipment that improves pilot situational awareness and other systems that
promote the overall airplane level of safety.
In most cases, means of compliance with proposed § 23.305 would follow an approach
somewhat similar to that used in the guidance material for current § 23.1309. Structural failures
resulting in fatalities are rare, occurring at a rate of approximately 3 x 10-8 per flight hour for
small airplanes. The reason for incorporating structural systems is not, in general, to improve
safety, but rather to reduce structural weight and thereby improve airplane performance.
Proposed § 23.305 would require that the level of safety must be the same for airplanes equipped
with systems that affect the structure and airplanes without such systems.
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An existing acceptable means of complying with proposed § 23.305 is provided in
several existing special conditions that address the interaction of systems and structures, for
example, FAA Special Condition 25-390-SC20. Most of these special conditions address load
alleviation systems. Load alleviation systems counteract the effects of gust and maneuver loads
and allow an applicant to design a lighter structure, thereby improving the performance and
utility of the airplane. These special conditions require that an applicant design the structure to
the required structural safety margins with the load alleviation system its normal functioning
state. The special conditions provide a means for an applicant to maintain the required structural
safety margins with the system in its failed state by adjusting the required safety margins based
on the likelihood of system failure. Systems that fail frequently require higher safety margins
than systems that rarely fail in order to maintain the same level of safety. The means of
compliance described in these special conditions allow an applicant to utilize the benefits of
structural systems and potentially eliminate weight and performance penalties associated with
structural hazards due to system failures.
Applicants who use the means of compliance described in the existing special conditions
would be able to use data developed for compliance with proposed § 23.1315. This data includes
identification of failure modes, identification of hazards resulting from the failure modes, and the
likelihood of the occurrence of the failure modes. With or without the proposed § 23.305
requirements, an applicant would have to account for structural performance with the system in
its normal operating and failed states and evaluate the system for compliance to the proposed
§ 23.1315. The FAA does not expect that additional detailed structural analysis would be
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http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSC.nsf/0/7B2D4B459E27848586257620006A6999?OpenDo
cument&Highlight=25-390-sc
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required for compliance with proposed § 23.305 other then the application of optional lower
safety margins to the structural performance analysis.
Proposed § 23.305 would allow an applicant to realize the value of structural and nonstructural systems and would potentially allow reduced structural weight of the airplane. The
magnitude of the weight reduction would depend on the functional characteristics of the systems
and the likelihood of system failures. The FAA believes proposed § 23.305 would reduce the
need for special conditions that deal with interaction of systems and structures, saving time and
effort for the FAA and the applicant.
iii. Proposed § 23.310, Structural Design Loads
Proposed § 23.310 would require an applicant to determine structural design loads
resulting from any externally or internally applied pressure, force, or moment, which may occur
in flight, ground and water operations, ground and water handling, and while the airplane is
parked or moored. Proposed § 23.310 would require the applicant to determine structural design
loads at all combinations of parameters on and within the boundaries of the structural design
envelope which result in the most severe loading conditions. Proposed § 23.310 would also
require the magnitude and distribution of these loads to be based on physical principles and
would be no less than service history has shown can occur within the structural design envelope.
Proposed § 23.310 would capture the safety intent of §§ 23.301, Loads; 23.302, Canard
or tandem wing configurations; 23.321, Flight Loads—General, paragraph (a); and 23.331,
Symmetrical flight conditions. Proposed § 23.310 would also capture the intent of several current
requirements for sound and physics-based engineering evaluations. An example is in current
§ 23.301(b), which requires that the forces and moments applied to the airplane must balance in
equilibrium, and the distribution of loads on the airplane must reasonably approximate actual
84
conditions. The part 23 regulations should not need to prescribe basic physical principles, sound
engineering judgment, and common sense. Proposed § 23.310 would place the burden on the
applicant to properly account for loads acting on the structure.
iv. Proposed § 23.315, Flight Load Conditions
Proposed § 23.315 would require an applicant to determine the loads resulting from
vertical and horizontal atmospheric gusts, symmetric and asymmetric maneuvers, and, for
multiengine airplanes, failure of the powerplant unit which results in the most severe structural
loads. Proposed § 23.315 would capture the safety intent of current §§ 23.333, Flight envelope,
paragraph (c); 23.341, Gust loads factors; 23.347, Unsymmetrical flight conditions; 23.349,
Rolling conditions; 23.351, Yawing conditions; 23.367, Unsymmetrical loads due to engine
failure; 23.421, Balancing loads; 23.423, Maneuvering loads; 23.425, Gust loads; 23.427,
Unsymmetrical loads; 23.441, Maneuvering loads; 23.443, Gust loads; and 23.445, Outboard
fins or winglets, paragraphs (b), (c), and (d).
These current part 23 sections establish prescriptive requirements for gust loads and
symmetrical, rolling, and yawing maneuvering loads, acting on the wing, horizontal tail, vertical
tail, and other lifting surfaces. Portions of the current sections, such as § 23.331(c), are
restatements of basic physical principles. Proposed § 23.315 would remove this language.
The FAA’s intent is not to lessen the structural load requirements. The current
prescriptive flight load requirements have established a level of safety where structural failure
due to overloading is rare. When structural failures do occur, the most common cause is airplane
upset or pilot disorientation in instrument meteorological conditions.
The FAA believes the prescriptive content of the current regulations, including the
modified Pratt formula for gust loads, the descriptions of symmetrical maneuvers, checked and
85
unchecked maneuvers, rolling maneuvers, and yawing maneuvers are more appropriate for
inclusion in means of compliance. Applicants who wish to propose alternate design loading
conditions should note that extensive data collection, testing, and evaluation may be necessary to
substantiate their proposal.
v. Proposed § 23.320, Ground and Water Load Conditions
Proposed § 23.320 would require an applicant to determine the loads resulting from taxi,
take-off, landing, and ground handling conditions occurring in normal and adverse attitudes and
configurations. Proposed § 23.320 would capture the safety intent of current §§ 23.471, Ground
Loads—General; 23.473, Ground load conditions and assumptions; 23.477, Landing gear
arrangement; 23.479, Level landing conditions; 23.481, Tail down landing conditions; 23.483,
One-wheel landing conditions; 23.485, Side load conditions; 23.493, Braked roll conditions;
23.497, Supplementary conditions for tail wheels; 23.499, Supplementary conditions for nose
wheels; 23.505, Supplementary conditions for skiplanes; 23.507, Jacking loads; 23.509, Towing
loads; 23.511, Ground load; unsymmetrical loads on multiple-wheel units; 23.521, Water load
conditions; 23.523, Design weights and center of gravity positions; 23.525, Application of loads;
23.527, Hull and main float load factors; 23.529 Hull and main float landing conditions; 23.531,
Hull and main float takeoff condition; 23.533, Hull and main float bottom pressures; 23.535,
Auxiliary float loads; 23.537, Seawing loads, and 23.753 Main float design.
The current requirements set forth prescriptive requirements for determining takeoff and
landing loads for airplanes operated on land, loads acting on floats and hulls for airplanes
operated on water, as well as ground handling loads, including jacking and towing conditions.
The current requirements also provide applicants with descriptions of the normal and adverse
86
operating conditions and configurations for which applicants must determine ground and water
loads.
The FAA believes that the prescriptive descriptions of the loading conditions, normal and
adverse conditions, and configurations are more appropriate for inclusion in means of
compliance. Applicants who wish to propose alternate design loading conditions should note that
extensive data collection, testing, and evaluation may be necessary to substantiate their proposal.
vi. Proposed § 23.325, Component Loading Conditions
Proposed § 23.325 would require an applicant to determine the loads acting on each
engine mount, flight control and high lift surface, and the loads acting on pressurized cabins.
Proposed § 23.325 would capture the safety intent of current §§ 23.345, High lift devices;
23.361, Engine torque; 23.363, Side load on engine mount; 23.365, Pressurized cabin loads;
23.371, Gyroscopic and aerodynamic loads; 23.373, Speed control devices; 23.391, Control
surface loads; 23.393, Loads parallel to hinge line; 23.395, Control system loads; 23.397, Limit
control forces and torques; 23.399, Dual control system; 23.405, Secondary control system;
23.407, Trim tab effects; 23.409, Tabs; 23.415, Ground gust conditions; 23.455, Ailerons; and
23.459, Special devices.
The current part 23 regulations establish prescriptive requirements for determining loads
acting on pressurized cabins, engine mounts and attachment structure, control surfaces, high lift
surfaces, and speed control devices. The FAA believes that these prescriptive requirements in the
current regulations are more appropriate for inclusion in means of compliance. However, in
proposed § 23.325, we have retained some of the prescriptive requirements for pressurized
cabins, including descriptions of combined loading conditions and additional factors of safety for
determining limit load.
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vii. Proposed § 23.330, Limit and Ultimate Loads
Proposed § 23.330 would describe how the applicant must determine the limit and
ultimate loads associated with the structural design loads. Proposed § 23.330 would capture the
safety intent of current §§ 23.301, Loads, paragraph (a); and 23.303, Factor of safety. These
current sections specify factors of safety for determining limit and ultimate loads.
Proposed § 23.330 retains the current 1.5 safety factor for ultimate loads. This safety
factor has resulted in a service history where structural failures due to applied static loads are
rare. The FAA believes the 1.5 factor of safety is critical to maintaining the current level of
safety.
Proposed § 23.330 would allow for additional special factors of safety to account for
material and manufacturing variability. Proposed § 23.330 would also allow alternate factors of
safety when showing compliance with occupant protection loading conditions and when showing
compliance with proposed § 23.305.
viii. Proposed § 23.400, Structural Strength
Proposed § 23.400 would require an applicant to demonstrate that the structure will
support limit and ultimate loads. Proposed § 23.400 would capture the safety intent of current
§§ 23.305, Strength and deformation; and 23.307, Proof of structure.
These current sections provide performance criteria for the structure when subjected to
limit and ultimate loads. Proposed § 23.400 would retain these performance criteria and would
require the applicant to demonstrate that the structure will meet these performance criteria. In
this context, “demonstrate” means the applicant must conduct structural tests to show
compliance with the structural performance requirements, unless the applicant shows that a
structural analysis is reliable and applicable to the structure. The FAA proposes not to retain the
88
“3 second” rule in proposed § 23.400. This prescriptive requirement in current § 23.305(b)
requires the applicant to demonstrate that the structure will support ultimate load for at least
three seconds. The FAA believes this prescriptive requirement is a statement of physical
principles and testing experience and is more appropriate for inclusion in means of compliance.
ix. Proposed § 23.405, Structural Durability
Proposed § 23.405 would require an applicant to develop and implement procedures to
prevent structural failures due to foreseeable causes of strength degradation, and to prevent rapid
decompression in airplanes with a maximum operating altitude above 41,000 feet. Proposed
§ 23.405 would also require an airplane to be reasonably capable of continued safe flight and
landing with foreseeable structural damage caused by high-energy fragments from an
uncontained engine or rotating machinery failure. Proposed § 23.405 would capture the safety
intent of current §§ 23.365(e), Pressurized cabin loads; 23.571, Metallic pressurized cabin
structures; 23.572, Metallic wing, empennage, and associated structures; 23.573, Damage
tolerance and fatigue evaluation of structure; 23.574, Metallic damage tolerance and fatigue
evaluation of commuter category airplanes; 23.575, Inspections and other procedures; and
23.627, Fatigue strength.
Proposed § 23.405(a) would require an applicant to develop and implement procedures to
prevent structural failures. These procedures may include the safe-life, damage tolerance, or failsafe design approaches described in the current regulations. An applicant can propose other
means of compliance, but these means must provide at least the same level of safety as current
means of compliance. Any new means of compliance must consider the airplane design,
manufacturing, operational, and maintenance environments. The FAA proposes implementing
these procedures by including them in the airplane’s Instructions for Continued Airworthiness.
89
The procedures must be able to prevent structural failures due to foreseeable causes of
strength degradation. Foreseeable causes include fatigue and corrosion in metallic structures, and
fatigue, delaminations, disbonds, and impact damage in composite structures. New material
systems or structural designs, such as additive manufacturing, may introduce new causes of
strength degradation and may require development of new and unique procedures to prevent
structural failures.
The current part 23 regulations use prevention of catastrophic failures as the safety intent
of the regulations. The word “catastrophic” is used throughout the current regulations, current
policy, and guidance material, especially in context of system safety analysis. To avoid any
potential conflict over the meaning of “catastrophic,” proposed § 23.405(a) would specify the
consequences we want to prevent. These consequences include the obvious performance criteria
for prevention of serious injuries, fatalities, or hull loss of the airplane.
The FAA also wants to prevent extended periods of operations with reduced safety
margins in those structural components whose failure could result in serious injuries, fatalities, or
hull loss. One situation that can result in reduced safety margins is fail-safe design. The FAA has
identified potential shortcomings in fail-safe designs, including an applicant’s difficulty to
anticipate all possible failure scenarios and ensure that all structural failures would be
immediately obvious and corrected before further flight. The concept of failures being obvious
and repaired before further flight is basic to the successful implementation of a fail-safe design.
This scenario could allow operation for extended periods with a passive structural failure and
reduced safety margins. If an applicant chooses fail-safe design as a means of compliance, an
applicant would have to ensure that the structure was not operating for extended periods with
reduced safety margins. An applicant may be able to apply safe-life or damage tolerance
90
principles to ensure that fail-safe structure maintains the required safety margins without
extended periods of operation with reduced safety margins through life limits or damage
tolerance based inspections.
Proposed § 23.405(b) would capture the safety intent of current § 23.365(e), requiring the
applicant to design the structure for sudden loss of pressurization after the failure of a door or
window in pressurized compartments. Proposed § 23.405(c) incorporates the safety intent of
current § 23.571(d). Our intention is that the damage tolerance methodology would remain the
accepted means of compliance. The FAA views damage tolerance as necessary since current
§ 23.571(d) and proposed § 23.405(c) require the applicant to assume that structural damage
exists in the pressurized cabin. However, proposed § 23.405(c) would allow for other means of
compliance as long as serious injuries and fatalities will be prevented. Examples of other means
of compliance might include requiring pilots and occupants to use oxygen masks or wear
pressurized flight suits when operating above 41,000 feet (12,497 meters). This means of
compliance could be acceptable in certain airplane designs, such as two-seat jet trainers.
Proposed § 23.405(d) would capture the safety intent of current § 23.903(b)(1) to
minimize hazards to the airframe resulting from turbine engine rotorburst. The FAA would move
the structural portion of the rotorburst evaluation from current § 23.903(b)(1) to proposed
§ 23.405(d) to ensure all structural requirements are contained in subpart C and to avoid potential
confusion over the structural rotorburst requirements in part 23.
Proposed § 23.405(d) would require an applicant to show that the design of the structure
would provide sufficient structural capability to allow continued safe flight and landing with
foreseeable structural damage caused by high energy fragments from an uncontained engine or
rotating machinery failure. The FAA recognizes that some high-energy fragment events may
91
result in catastrophic failures that may not be avoidable and that complete elimination of the
hazards resulting from high energy fragment events may not be possible.
An applicant would be required to address other sources of high energy rotating
machinery fragments in the proposed structural rotorburst requirements. Our intent is to ensure
an adequate regulatory framework for applications of electrical propulsion systems and other
unique and novel approaches to propulsion, which may release high-energy fragments.
Applicants who have shown compliance with current § 23.903(b)(1) would be able to
show compliance with proposed § 23.405(d). Applicants should note that previous certification
programs with turbine engine installations have been able to show that the airplane structure is
capable of continued safe flight and landing following a rotorburst event. AC 23-13A, Fatigue,
Fail-Safe, and Damage Tolerance Evaluation of Metallic Structure for Normal, Utility,
Acrobatic, and Commuter Category airplanes, provides guidance on the required structural
evaluation.
x. Proposed § 23.410, Aeroelasticity
Proposed § 23.410 would require an airplane to be free from flutter, control reversal, and
divergence at all speeds within and sufficiently beyond the structural design envelope, for any
configuration and condition of operation, accounting for critical degrees of freedom, and any
critical failures or malfunctions. Proposed § 23.410 would also require an applicant to establish
tolerances for all quantities that affect flutter.
Proposed § 23.410 would capture the safety intent of the current §§ 23.629, Flutter;
23.677, Trim systems, paragraph (c); and 23.687, Spring devices, in part. Specifically, proposed
§ 23.410 would address the safety intent of these rules by requiring freedom from flutter, control
reversal, and divergence, while accounting for all speeds, configurations, modes, and failures,
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and to establish tolerances on anything affecting flutter. The current § 23.629(a) states that
freedom from flutter, control reversal, and divergence must be shown by the methods of
§ 23.629(b) and (c) or (d). These paragraphs are prescriptive in nature and some portions are
applicable only to very specific types of designs and include speed limitations. Therefore, these
paragraphs are more appropriate as means of compliance.
The current § 23.629(e) requires the evaluation of whirl mode flutter. Since this is
another flutter mode, it must be accounted for when an airplane is determined to be free from
flutter. The current § 23.629(f), (g), (h), and (i) provide instructions on how to evaluate 1) certain
airplane design types, 2) designs employing certain methods (fail-safe or damage tolerant), or 3)
airplanes incorporating design modifications. The current § 23.677(c) requires either that the tab
be balanced or that the tab controls be irreversible. Additionally, it requires that irreversible tab
systems have adequate rigidity and reliability. These are very specific design solutions for
ensuring freedom from flutter. The current § 23.687 requires that the reliability of spring devices
used in control systems be established by tests unless its failure would not cause flutter. This is a
method of compliance to ensure freedom from flutter. All of these current requirements are more
appropriate as means of compliance because they describe how to ensure freedom from flutter,
control reversal, and divergence. They are not the safety intent, but just one method to achieve
the safety intent. As such, they serve only specific designs utilizing current methods, and may or
may not be adequate for innovative designs or accommodate new analytical methods or testing
techniques.
xi. Proposed § 23.500, Structural Design
Proposed § 23.500 would require an applicant to design each part, article, and assembly
for the expected operating conditions of the airplane. Proposed § 23.500 would require the
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design data to adequately define the part, article, or assembly configuration, its design features,
and any materials and processes used. Proposed § 23.500 would require an applicant to
determine the suitability of each design detail and part having an important bearing on safety in
operations. Proposed § 23.500 would also require the control system to be free from—

Jamming;

Excessive friction, and

Excessive deflection when the control system and its supporting structure are
subjected to loads corresponding to the limit airloads when the primary controls
are subjected to the lesser of the limit airloads or limit pilot forces and when the
secondary controls are subjected to loads not less than those corresponding to
maximum pilot effort.
Proposed § 23.500 would capture the safety intent of the current §§ 23.601, Design and
Construction—General; 23.603, Materials and workmanship, paragraph (b); 23.671, Control
Systems—General, paragraph (a); 23.683, Operation tests; 23.685, Control system details;
23.687, Spring devices, in part; and 23.689, Cable systems. These current requirements explain
methods and techniques to ensure an adequate design. The proposed rule would require an
applicant to produce an adequate design without specifying how. The prescriptive language
within these current sections noted above, are more appropriate for a means of compliance.
xii. Proposed § 23.505, Protection of Structure
Proposed § 23.505 would require an applicant to protect each part of the airplane,
including small parts such as fasteners, against deterioration or loss of strength due to any cause
likely to occur in the expected operational environment. Proposed § 23.505 would require each
part of the airplane to have adequate provisions for ventilation and drainage and would require
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an applicant to incorporate a means into the airplane design to allow for required maintenance,
preventive maintenance, and servicing.
Proposed § 23.505 would capture the safety intent of the current §§ 23.607, Fasteners;
23.609, Protection of structure; and 23.611, Accessibility. These current requirements explain
methods and techniques to ensure an adequate design. This proposed rule would require the
applicant to produce an adequate design without specifying how to accomplish it. The
prescriptive language within these current sections is more appropriate as a means of
compliance.
xiii. Proposed § 23.510, Materials and Processes
Proposed § 23.510 would require an applicant to determine the suitability and durability
of materials used for parts, articles, and assemblies, the failure of which could prevent continued
safe flight and landing, while accounting for the effects of likely environmental conditions
expected in service. Proposed § 23.510 would require the methods and processes of fabrication
and assembly used to produce consistently sound structures and, if a fabrication process requires
close control to reach this objective, an applicant would have to perform the process under an
approved process specification. Additionally, proposed § 23.510 would require an applicant to
justify the selected design values to ensure material strength with probabilities, account for—

The criticality of the structural element; and

The structural failure due to material variability, unless each individual item is
tested before use to determine that the actual strength properties of that particular
item would equal or exceed those used in the design, or the design values are
accepted by the Administrator.
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Proposed § 23.510 would require a determination of required material strength properties
to be based on sufficient tests of material meeting specifications to establish design values on a
statistical basis. Proposed § 23.510 would also require an applicant to determine the effects on
allowable stresses used for design if thermal effects were significant on an essential component
or structure under normal operating conditions.
Proposed § 23.510 would capture the safety intent of the current §§ 23.605, Fabrication
methods and 23.613, Material strength properties and design values. These current requirements
explain methods and techniques to ensure adequate materials and process controls. This
proposed rule would require the applicant to ensure the resulting materials and processes are
adequate without specifying how. The prescriptive language within the current sections is more
appropriate as a means of compliance.
xiv. Proposed § 23.515, Special Factors of Safety
Proposed § 23.515 would require an applicant to determine a special factor of safety for
any critical design value that was uncertain, used for a part, article, or assembly likely to
deteriorate in service before normal replacement, or subject to appreciable variability because of
uncertainties in manufacturing processes or inspection methods. Proposed § 23.515 would
require an applicant to determine a special factor of safety using quality controls and
specifications that accounted for each structural application, inspection method, structural test
requirement, sampling percentage, and process and material control. Proposed § 23.515 would
require an applicant to apply any special factor of safety in the design for each part of the
structure by multiplying each limit load and ultimate load by the special factor of safety.
Proposed § 23.515 would capture the safety intent of current §§ 23.619, Special factors;
23.621, Casting factors; 23.623, Bearing factors; 23.625, Fitting factors; 23.657, Hinges;
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23.681(b), Limit load static test (in part); and 23.693, Joints. These current requirements explain
methods and techniques to ensure adequate special factors are used and the proposed rule would
simply require the applicant to determine and apply adequate special factors without specifying
what these are. The prescriptive language within the current sections is more appropriate as a
means of compliance.
xv. Proposed § 23.600, Emergency Conditions
Proposed § 23.600 would require the airplane, even if damaged in emergency landing
conditions, to provide protection to each occupant against injury that would preclude egress.
Proposed § 23.600 would require the airplane to have seating and restraints for all occupants,
consisting of a seat, a method to restrain the occupant’s pelvis and torso, and a single action
restraint release, which meets its intended function and does not create a hazard that could cause
a secondary injury to an occupant. Proposed § 23.600 would require the airplane seating,
restraints, and cabin interior to account for likely flight and emergency landing conditions.
Additionally, they could not prevent occupant egress or interfere with the operation of the
airplane when not in use.
Proposed § 23.600 would require each baggage and cargo compartment be designed for
its maximum weight of contents and for the critical load distributions at the maximum load
factors corresponding to the determined flight and ground load conditions. Proposed § 23.600
would also require each baggage and cargo compartment to have a means to prevent the contents
of the compartment from becoming a hazard by impacting occupants or shifting, and to protect
any controls, wiring, lines, equipment, or accessories whose damage or failure would affect
operations.
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Proposed § 23.600 would capture the safety intent of current §§ 23.561, Emergency
Landing Conditions—General; 23.562, Emergency landing dynamic conditions; 23.785, Seats,
berths, litters, safety belts, and shoulder harnesses; and 23.787, Baggage and cargo
compartments. The prescriptive language within these current sections are more appropriate as a
means of compliance, and thus would allow flexibility for new technology to be available in new
part 23 airplanes in a timely manner.
Occupant safety for aviation has progressed incrementally over the years. This has
resulted in rulemaking that has enhanced safety for individual system components, but not in an
integrated fashion. Modeling and analysis techniques have matured to a point that may allow
evaluation of more crash scenarios and crashworthiness components as an integrated system. The
FAA has relied on many industry studies to develop current occupant safety rules. These studies
evaluated characteristics of actual accidents, full-scale aircraft drop testing, and dynamic seat
testing on a sled. When dynamic seat testing began, determination of an adequate generic floor
impulse that represented a survivable aircraft crash was established. As an alternative to current
crashworthiness requirements, the proposed rule would allow for evaluation of the conditions of
likely impacts, assessment of vehicle response, and ultimately, evaluation of occupant reaction to
vehicle impact and vehicle response.
Technology used in aviation crashworthiness, in a large part, has come from the
automotive industry. The automotive industry has analyzed crashworthiness components as a
system for many years. The automotive industry generally has a more developed crashworthiness
analysis capability than that used in the aviation industry. This advanced crashworthiness
analysis capability has evolved primarily because of the—

Public expectation for automobile safety;
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
Higher general public likelihood and exposure to automobile accidents; and

High automobile production rates allow for multiple actual full-vehicle crash tests
that result in very accurate crash impulse data from the outer surface of the
vehicle all the way to the occupant.
Because of these facts, automotive designers know accurate impulses and the specific vehicle
response for impact conditions. Furthermore, this data can be extrapolated to consider many
more accident scenarios. Automotive safety requirements progressively add new impact scenario
requirements and enhanced impulse magnitudes, thus requiring more industry innovation. This
innovation has enabled rapid advances in automotive occupant protection systems.
Automotive safety begins at the outside of the vehicle, evaluating the entire system’s
response. In contrast, aircraft manufacturers have used essentially the same generic designed
pulse imparted at the cabin floor for the last 25 years. The same impulse applies to all GA
airplanes independent of the structure below the cabin floor and the aircraft’s stall speed, unless
the stall speed is greater than 61 knots. Determining airplane crashworthiness is a more complex
process than determining automotive crashworthiness because of higher impact speeds, lighter
weight structures, and the effect of the third dimension of altitude on the aircraft. Dynamic seat
testing has improved crashworthiness in aviation; however, the FAA believes that newer means
of evaluating the full aircraft response to crash conditions via modeling, newer materials, and
new technologies promise to offer improved features, evaluation, and accuracy that would
facilitate consideration of more crash scenarios and evaluation of more variables that could
improve survivability.
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The NTSB produced a series of reports, called the General Aviation Crashworthiness
Project21, in the 1980s that evaluated over 21,000 GA airplane crashes that occurred between
1972 and 1981. The NTSB evaluated airplane orientation, impact magnitudes, and survival rates
and factors on many of these accidents in order to provide information to support changes in
crashworthiness design standards for seating and restraint systems in GA airplanes. These reports
also established conditions approximating survivable accidents, and categorized factors that
would have the largest impact on safety. These reports further illuminated the various
crashworthiness systems and their respective impact to overall safety. Amendment 23-36
(53 FR 30802, August 15, 1988), to part 23 referenced these reports for dynamic seats but did
not adopt a systems-approach to evaluating crashworthiness of an airplane design.
The NTSB reports identified several factors that would enhance safety. All of these
factors working together as a system should result in a safer airplane. However, the assessment
indicated that shoulder harnesses offer the fastest individual improvement for safety. The FAA
codified the shoulder harnesses requirement in amendments 23-19 (42 FR 20601, June 16, 1977)
and 23-32 (50 FR 46872, November 13, 1985), for newly manufactured airplanes. The FAA also
issued policy statement ACE-00-23.561-0122, Methods of Approval of Retrofit Shoulder Harness
Installations in Small Airplanes, to streamline the process for retrofitting older airplanes.
Survivable volume is another critical factor to survival. Survivable volume is the ability
of the airframe to protect the occupants from external intrusion or cabin crushing during and
after the accident sequence. There were several observed accidents in the NTSB study where
conventional aircraft construction simply crushed an otherwise restrained occupant.
Crashworthiness regulations have never included survivable volume as a factor, except for
21
22
See www.regulations.gov (Docket # FAA-2015-1621)
See www.regulations.gov (Docket # FAA-2015-1621)
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aircraft turnover. Airplane designs should provide the space needed for the protection and
restraint of the occupants. A compromised survivable volume could cause occupant impact with
objects in the cabin. This is one of the first steps in the analysis of airplane crashworthiness.
Additional data from the NTSB General Aviation Crashworthiness Project suggested that
energy-absorbing seats that protect the occupant from vertical loads could enhance occupant
survivability and work to prevent serious injury, thereby enhancing odds for egress and
preventing many debilitating long-term injuries. The FAA established dynamic seat testing
requirements in amendment 23-36 for airplanes certificated under part 23. Energy absorbing
seats benefit a smaller portion of accident occupants because accident impacts with larger
vertical components tend to reduce occupant survival odds. Energy attenuation from vertical
forces, both static and dynamic, has been important to crashworthiness regulations within the
past 25 years. Seat deformation throughout the emergency landing sequence is acceptable if the
load path through attachment, seat, and restraint remains continuous. Coupling the seat
performance to the rest of the airframe response is important to the enhancement and
understanding of occupant survivability. The FAA believes that allowing designers to consider a
particular airframe’s unique deformation in a crash, the designers can create a safer cabin for the
occupants. Using unique airframe deformations would result in more accurate accident floor
impulses and may allow evaluation of crash impulses in multiple directions; instead of only two
directions considered in current certification.
Occupant restraints must maintain integrity, stay in place on the occupant throughout the
event, properly distribute loads on the occupant, and restrain the occupant by mitigating
interaction with other items in the cabin. Restraints originally were comprised of lap belts.
Shoulder harnesses were later required as discussed above. Newer technology that enhances or
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supplements the performance of restraints, like airbags and consideration of items in the cabin
that the occupant might impact, are now being considered for inclusion in designs. The use of
airbags has greatly increased passenger safety in automobiles, which offer protection in much
more severe impacts and in impacts from multiple directions, and could be a viable option for
airplanes as well.
Seat retention in airplanes is a factor identified as another basic building block for
crashworthiness. The NTSB reports shows more than a quarter of otherwise-survivable accidents
included instances where the seats broke free at the attachment to the airplane, resulting in
fatalities or serious injuries. Dynamic seat testing requirements address the ability of seat
assemblies to remain attached to the floor, even when the floor shifts during impact. Pitching and
yawing of the seat tracks during dynamic seat tests demonstrates the gimbaling and flexibility of
the seat.
All of the aforementioned safety considerations must work together to enhance occupant
safety and survivability. The FAA believes that evaluating occupant safety, as a whole system,
would allow for a better understanding of vehicle performance in an emergency landing,
enabling the incorporation of innovative technology. The transportation industry has made
significant progress with energy absorbing seats and restraint technology. The FAA believes
enhanced cabin strength that improves survivable volume, coupled with better restraint
technology and refined energy absorbing seats, would be key factors in improving expansion of
the survivable accident envelope. These factors and additional considerations were included in
the Small Airplane Crashworthiness Design Guide23. This guide was prepared for the Advanced
23
See www.regulations.gov (Docket # FAA-2015-1621)
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General Aviation Transports Experiments and the National Aerospace and Space Administration
and addresses the concept of designing crashworthiness into an airplane design as a system.
In order to evaluate an accident from an occupant’s perspective, the emergency landing
condition must first be defined, starting with the conditions external to the aircraft. In most
survivable accidents, the pilot is able to maintain control of the aircraft prior to impact.
Accidents where the airplane impacts the ground out of control are typically much less
survivable. Speed and impact orientation are significant factors in crash survivability. Therefore,
considerations for impact beyond a controllable impact are beyond the scope of these proposed
regulations. The slowest forward speed that any fixed wing airplane can fly is its stall speed. This
stall speed can vary with airplane configuration and weight, but represents the most universal
parameter for impact speed and energy attenuation at impact. For this reason, stall speed is the
starting point for consideration of expected impact conditions.
Orientation of impact can vary with pitch, yaw, terrain angle, and angle of flight path and
becomes dynamic as the pilot loses control effectiveness at stall. The result is the airplane impact
angle can result in a combination of horizontal and vertical loads and impulses that vary widely.
Angle of impact, the line of the center of mass with respect to the angle of the impact surface,
can also affect the amount of energy absorbed or transmitted to the occupant.
An accident impulse is a dynamic event that rapidly loads and unloads the structure.
Dynamic impacts accurately represent the impact event, often including load levels far
surpassing the static load requirements. Dynamic testing is also subject to a wide variation of
results due to the unpredictable dynamic responses of varying construction methods and
materials, resulting in complicated modeling and analysis. This contrasts with static load tests
that load the structure slowly, maintain that load at high levels, are generally simpler, and often
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provide adequate demonstration of part strength. Static analysis is generally more reliable with
both testing and modeling; however, it does not capture the nature of rapid loading. Some
combination of dynamic and static testing allows for the best understanding of airplane behavior
during an accident.
Compliance with the proposed rule could be shown using conventional means of
compliance like dynamic testing of seats, and static testing of other components using the
prescriptive methods contained in the current part 23. Alternative compliance methods could
include analysis or modeling supported by testing using an airframe coupled with the airplane’s
performance envelope, viewing the entire interaction of ground, airplane, and occupant, thus
using a more complete systemic approach to achieve improved protection.
Proposed § 23.600(a) is intended to provide structural performance that protects the
occupant during an emergency landing while accounting for only static loads and assuming all
safety equipment is in use. The proposed section would capture the safety intent of the current
§ 23.561. As noted earlier, static loads are generally lower than peak dynamic loads; however,
they may offer a more-easily predictable loading condition and are generally of longer duration
such that the structure can fully react to the load. The landing conditions should consider
possible accident sequence variables at impact, including restraint of items of mass within the
cabin, directions of loading along or about the three axes, and airframe response with respect to
the occupants and effects of airframe deflection during an emergency landing. Effects of
emergency landing on the airplane should also be considered to include the effect of airframe
damage and how static loads would affect egress and survivable cabin volume. Items of mass
within the cabin and rear mounted engines have also been traditionally considered using even
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higher static loads as an additional factor of safety to ensure that these items of mass are
restrained and would be among the last items to come free in an accident.
Proposed § 23.600(b) is intended to provide boundary conditions for the emergency
landing sequence for both static and dynamic load considerations. The proposed section would
capture the safety intent of the current §§ 23.561 and 23.562. The airplane stall speed limits the
maximum forward impact speed. The emergency landing condition assumes the pilot maintains
airplane control at or near final impact, thereby limiting impact velocity.
Proposed § 23.600(c) would capture the survivability factors for the occupant in the cabin
during the emergency landing sequence and would capture the safety intent of current § 23.562.
These factors include proper use and loading of seats and restraints, and the interaction of the
occupants with each other and the cabin interior. Survivability is determined upon the occupant’s
interaction with the interior, seat, and restraints, and bounded by established human injury
criteria.
Proposed § 23.600(d) would provide the framework for seats and occupant restraints and
would require simplified seat and restraint requirements for all occupants. This proposed section
would capture the safety intent of current § 23.785.
Proposed § 23.600(e) would establish requirements for baggage and cargo compartments
and the restraint of contents. The proposed section would capture the safety intent of current
§ 23.787.
xvi. Current Subpart C Regulations Relocated to Other Proposed Subparts
As discussed, the FAA proposes removing current §§ 23.561, 23.562, 23.785, and
23.787. Also, this proposal would consolidate the safety intent of these crashworthiness
regulations in proposed § 23.600.
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4. Subpart D – Design and Construction
a. General Discussion
The FAA proposes restructuring current subpart D to retain the requirements for flight
control systems, along with their attachment to the structure and landing gear, and occupant
safety other than structural requirements. The FAA proposes to align structural requirements,
found in current §§ 23.601 through 23.659, to proposed subpart C. Aspects that directly affected
the pilot’s interface with the airplane, such as the throttle shape, would be relocated to proposed
§ 23.1500, Flightcrew Interface.
The FAA also proposes, in those sections where there are requirements specific to the
current commuter category, to use certification level 4. In those sections where there are current
requirements specific to multiengine jets over 6,000 pounds, the FAA proposes requirements for
certification level 3, high-speed multiengine airplanes as discussed earlier in this proposal. Refer
to appendix 1 of this preamble for a cross-reference table detailing how the current regulations
are addressed in the proposed part 23 regulations.
The subpart D organization was more complex than other subparts due to the relocation
and removal of many requirements at the sub-paragraph level. To reduce confusion, the specific
discussion of subpart D changes is shown in a cross reference table at the end of the specific
discussion section below rather than the Relocation and Removal paragraphs in other subparts.
b. Specific Discussion of Changes
i. Proposed § 23.700, Flight Controls Systems
Proposed § 23.700 would require an applicant to design airplane flight control systems to
prevent major, hazardous, and catastrophic hazards. Proposed § 23.700 would require an
applicant to design trim systems to prevent inadvertent, incorrect, or abrupt trim operation. In
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addition, proposed § 23.700 would require an applicant to design trim systems to provide a
means to indicate—

The direction of trim control movement relative to airplane motion;

The trim position with respect to the trim range;

The neutral position for lateral and directional trim; and

For all airplanes except simple airplanes, the range for takeoff for all applicant
requested center of gravity ranges and configurations.
Proposed § 23.700 would also require an applicant to design trim systems to provide
control for continued safe flight and landing when any one connecting or transmitting element in
the primary flight control system failed, except for simple airplanes. Additionally, proposed
§ 23.700 would require an applicant to design trim systems to limit the range of travel to allow
safe flight and landing, if an adjustable stabilizer is used.
Furthermore, proposed § 23.700 would require the system for an airplane equipped with
an artificial stall barrier system to prevent uncommanded control or thrust action and provide for
a preflight check. The FAA also proposes requiring an applicant seeking certification of a
certification level 3 high-speed or certification level 4 airplane to install a takeoff warning
system on the airplane, unless the applicant demonstrates that the airplane, for each
configuration, could takeoff at the limits of its trim and flap ranges.
Proposed § 23.700(b)(3) would also allow an exception for simple airplanes from the
requirement to provide control for continued safe flight and landing when any one connecting or
transmitting element in the primary control system fails. This would provide a level of safety
equivalent to that specified in EASA’s CS-VLA. Last, proposed § 23.700(d) would maintain the
level of safety in the current requirements for a takeoff warning system.
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Proposed § 23.700 would capture the safety intent of current §§ 23.677, Trim systems,
paragraphs (a), (b), and (d); 23.689, Cable systems, paragraphs (a) and (f); 23.691, Artificial stall
barrier system, paragraphs (a), (b), (d), (e) and (f); 23.697, Wing flap controls, paragraphs (a);
and 23.703, Takeoff warning system, paragraphs (a) and (b). This proposed section would apply
to the function, usability, and hazard levels of all mechanical, electrical, or electronic control
systems. The certification levels proposed in this NPRM would be incorporated into the
mechanical, electrical, or electronic control systems to maintain the differences in airplanes
certificated under part 23 (i.e., weight and powerplant.)
ii. Proposed § 23.705, Landing Gear Systems
Proposed § 23.705 would require an airplane’s landing gear and retracting mechanism be
able to withstand operational and flight loads. Proposed § 23.705 would require an airplane with
retractable landing gear to have a positive means to keep the landing gear extended and a
secondary means for extending the landing gear that could not be extended using the primary
means. Proposed § 23.705 would also require a means to inform the pilot that each landing gear
is secured in the extended and retracted positions. Additionally, proposed § 23.705 would require
an airplane, except for airplanes intended for operation on water, with retractable landing gear to
also have a warning to the pilot if the thrust and configuration is selected for landing and yet the
landing gear is not fully extended and locked.
Furthermore, if the landing gear bayis used as the location for equipment other than the
landing gear, proposed § 23.705 would require that equipment be designed and installed to avoid
damage from tire burst and from items that may enter the landing gear bay. Proposed § 23.705
would also require the design of each landing gear wheel, tire, and ski account for critical loads
and would require a reliable means of stopping the airplane with kinetic energy absorption within
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the airplane’s design specifications for landing. For certification level 3 high-speed multiengine
and certification level 4 multiengine airplanes, proposed § 23.705 would require the braking
system to provide kinetic energy absorption within the design of the airplane specifications for
rejected takeoff as the current rules do for multiengine jets over 6,000 pounds and commuter
category airplanes.
Proposed § 23.705 would capture the safety intent of current §§ 23.729, Landing gear
extension and retraction system, paragraphs (a), (b), (c), and (e); 23.731, Wheels; 23.733, Tires,
paragraph (a); 23.735, Brakes, paragraphs (a), (b), and (e); 23.737, Skis. The FAA proposes to
combine the fixed and retractable landing gear systems into the proposed section, which would
apply to the function, usability, and hazard levels of all mechanical, electrical, or electronic
landing gear systems.
iii. Proposed § 23.710, Buoyancy for Seaplanes and Amphibians
Proposed § 23.710 would require airplanes intended for operations on water to provide
buoyancy of 80 percent in excess of the buoyancy required to support the maximum weight of
the airplane in fresh water. Proposed § 23.710 would also require airplanes intended for
operations on water to have sufficient watertight compartments so the airplane will stay afloat at
rest in calm water without capsizing if any two compartments of any main float or hull are
flooded.
Proposed § 23.710 would capture the safety intent of current §§ 23.751(a), Main float
buoyancy; 23.755, Hulls; and 23.757, Auxiliary floats. The FAA proposes combining the floats
or hulls landing gear systems into the proposed section and having it apply to the function,
usability, and hazard levels of hulls and floats. The existing rule requires at least four watertight
compartments of approximately equal volume, which the FAA proposes to remove because they
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are specific design requirements and are addressed in the proposed performance-based
requirements.
To encourage the installation of buoyancy systems with new safety enhancing technology
and streamlining the certification process, the FAA proposes removing most of the current
prescriptive requirements and the detailed means of compliance for these requirements from the
current part 23 and replacing them with performance-based regulations. The FAA expects the
current means of compliance would continue to be used for the traditional airplane designs under
part 23.
iv. § 23.750, Means of Egress and Emergency Exits
Proposed § 23.750 would require the airplane cabin exit be designed to provide for
evacuation of the airplane within 90 seconds in conditions likely to occur, excluding ditching,
following an emergency landing. For ditching, proposed § 23.750 would require the cabin exit
for all certification levels 3 and 4 multiengine airplanes be designed to allow evacuation in 90
seconds. Proposed § 23.750 would require each exit to have a simple and obvious means, marked
inside and outside the airplane, to be opened from both inside and outside the airplane, when the
internal locking mechanism is in the locked position.
Proposed § 23.750 would also require airplane evacuation paths to protect occupants
from serious injury from the propulsion system, and require that doors, canopies, and exits be
protected from opening inadvertently in flight. Proposed § 23.750 would preclude each exit from
being obstructed by a seat or seat back, unless the seat or seat back could be easily moved in one
action to clear the exit. Proposed § 23.750 would also require airplanes certified for aerobatics to
have a means to exit the airplane in flight.
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Proposed § 23.750 would capture the safety intent of current §§ 23.783, Doors,
paragraphs (a), (b), (c), and (d); 23.791, 23.803, Emergency evacuation, paragraph (a); 23.805,
Flightcrew emergency exits; 23.807, Emergency exits except Paragraphs (a)(3), (b)(1), (c), (d)(1)
and (d)(4); 23.811, Emergency exit marking; 23.812, Emergency lighting; 23.813, Emergency
exit access, paragraph (a); and 23.815, Width of aisle; and CS-VLA-783, Exits. This proposed
rule would incorporate the requirements for all door and emergency exits and remove specified
design solutions and means of compliances.
To encourage the installation of egress and emergency exits with new safety enhancing
technology and streamline the certification process, the FAA proposes removing most of the
current prescriptive requirements and the detailed means of compliance for these requirements
from the current part 23. The FAA expects that the current prescriptive means of compliance
would continue to be used for traditional part 23 airplane designs.
The FAA would continue to accept an airplane designed to meet these prescriptive design
constraints as means of compliance to meet the proposed performance standard. However, if an
airplane did not meet the prescriptive design constraints, the applicant could propose its own
means of compliance to show compliance with the proposed performance standard. Historically,
the FAA has accepted an emergency evacuation demonstration in less than 90 seconds as an
ELOS for airplanes that did not meet the prescriptive design requirements in the current part 23
regulations. AC 20-118A, Emergency Evacuation Demonstration, contains an acceptable means
of compliance for the 90-second requirement for emergency evacuation.
v. Proposed § 23.755, Occupant Physical Environment
Proposed § 23.755 would require an applicant to design the airplane to allow clear
communication between the flightcrew and passengers and provide a clear, sufficiently
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undistorted external view to enable the flightcrew to perform any maneuvers within the operating
limitations of the airplane. Proposed § 23.755 would also require an applicant to design the
airplane to protect the pilot from serious injury due to high energy rotating failures in systems
and equipment, and protect the occupants from serious injury due to damage to windshields,
windows, and canopies.
Additionally, proposed § 23.755 would require, for certification level 4 airplanes, each
windshield and its supporting structure directly in front of the pilot to withstand the impact
equivalent of a two-pound bird at maximum approach flap airspeed and allow for continued safe
flight and landing after the loss of vision through any one panel.
Furthermore, proposed § 23.755 would require any installed oxygen system to include a
means to determine whether oxygen is being delivered and a means for the flightcrew to turn on
and shut off the oxygen supply, and the ability for the flightcrew to determine the quantity of
oxygen available. Proposed § 23.755 would also require any installed pressurization system to
include a pressurization system test and a warning if an unsafe condition exists.
Proposed § 23.755 would capture the safety intent of current §§ 23.771, Pilot
compartment, paragraphs (b) and (c); 23.775, Windshields and windows, paragraphs (a),(b), (c),
(d), and (h); 23.831, Ventilation; 23.841, Pressurized cabins, paragraphs (a), (b)(6), (c) and (d);
23.843, Pressurization tests; 23.1441, Oxygen equipment and supply, paragraphs (c), (d) and (e);
23.1443, minimum mass flow of supplemental oxygen, paragraphs (a), (b), and (c); 23.1445;
Oxygen distribution system; 23.1447, Equipment standards for oxygen dispensing units,
paragraphs (a) through (d) and (f); 23.1449, means of determining use of oxygen; and 23.1461,
Equipment containing high energy rotors. Current part 23 regulations contain prescriptive
language and means of compliance for the occupant physical environment requirements. The
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FAA proposes to remove the specific requirements to allow an applicant to specify the means of
compliance for the physical needs of the occupants including temperature, ventilation,
pressurization, supplemental oxygen, etc. For example, current § 23.831(a) requires carbon
monoxide not exceeding one part in 20,000 parts of air. The FAA proposes revising this by
requiring breathable atmosphere without hazardous concentrations of gases and vapors.
vi. Proposed § 23.800, Fire Protection Outside Designated Fire Zones
Proposed § 23.800 would require that insulation on electrical wire and electrical cable
outside designated fire zones be self-extinguishing. Proposed § 23.800 would require airplane
cockpit and cabin materials in certification levels 1, 2, and 3 be flame-resistant. Proposed
§ 23.800 would require airplane cockpit and cabin materials in certification level 4 airplanes be
self-extinguishing. Proposed § 23.800 would also require that airplane materials in the baggage
and cargo compartments, which are inaccessible in flight and outside designated fire zones, be
self-extinguishing. Proposed § 23.800 would require that any electrical cable installation that
would overheat in the event of circuit overload or fault be flame resistant. Additionally, proposed
§ 23.800 would preclude thermal acoustic materials outside designated fire zones from being a
flame propagation hazard. Proposed § 23.800 would also require sources of heat that are capable
of igniting adjacent objects outside designated fire zones to be shielded and insulated to prevent
such ignition.
Proposed § 23.800 would require airplane baggage and cargo compartments, outside
designated fire zones, to be located where a fire would be visible to the pilots, or equipped with a
fire detection system and warning system, and be accessible for the manual extinguishing of a
fire, have a built-in fire extinguishing system, or be constructed and sealed to contain any fire
within the compartment.
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Proposed § 23.800 would require a means to extinguish any fire in the cabin, outside designated
fire zones, such that the pilot, while seated, could easily access the fire extinguishing means, and
for certification levels 3 and 4 airplanes, passengers would have a fire extinguishing means
available within the passenger compartment. Where flammable fluids or vapors might escape by
leakage of a fluid system, proposed § 23.800 would require each area, outside designated fire
zones, be defined and have a means to make fluid and vapor ignition, and the resultant hazard, if
ignition occurs, improbable. Additionally, proposed § 23.800 would also require combustion
heater installations outside designated fire zones be protected from uncontained fire.
Proposed § 23.800 would capture the safety intent of current §§ 23.851, Fire
extinguishers, paragraphs (a) and (b); 23.853, Passenger and crew compartment interiors,
Paragraphs (a), (d)(3)(i), (d)(3)(iii) and (d)(3)(iv), (e), and (f); 23.855, Cargo and baggage
compartment fire protection; 23.856, Thermal/acoustic insulation materials; 23.859, Combustion
heater fire protection, paragraph (a); 23.863, Flammable fluid fire protection, paragraphs (a) and
(d); 23.1359, Electrical system fire protection, paragraph (c); 23.1365, Electric cables and
equipment, paragraph (b); 23.1383, Taxi and landing lights, paragraph (d); 23.1385, Position
light system installation, paragraph (d). It would also capture the safety intent of CS-VLA-853,
Compartment interiors. Proposed § 23.800 would incorporate the requirements for flammability
of all subpart D and F systems and equipment outside designated fire zones needed for continued
safe flight and landing and remove specified design solutions and means of compliances.
vii. Proposed § 23.805, Fire Protection in Designated Fire Zones
Proposed § 23.805 would require flight controls, engine mounts, and other flight
structures within or adjacent to designated fire zones be capable of withstanding the effects of a
fire. Proposed § 23.805 would require engines inside designated fire zones to remain attached to
114
the airplane in the event of a fire or electrical arcing. Proposed § 23.805 would also require
terminals, equipment, and electrical cables, inside designated fire zones, used during emergency
procedures, be fire-resistant.
Proposed § 23.805 would capture the safety intent of current § 23.865, Fire protection of
flight controls, engine mounts, and other flight structure and § 23.1359(b), Electrical system fire
protection. The intent of proposed § 23.805 is to protect flight controls, engine mounts, and other
flight structure as well as electrical cables, terminals and equipment from the effects of fire in
designated fire zones.
viii. Proposed § 23.810, Lightning Protection of Structure
Proposed § 23.810 would preclude primary structure failure caused by exposure to the
direct effects of lightning, that could prevent continued safe flight and landing for airplanes
approved for IFR. Proposed § 23.810 would require airplanes approved only for VFR to achieve
lightning protection by following FAA accepted design practices found in FAA issued advisory
circulars and in FAA accepted consensus standards.
Proposed § 23.810 would capture the safety intent of the current § 23.867(a) and (c),
Electrical bonding and protection against lightning and static electricity. The FAA proposes
adopting the structure requirements in part 23, amendment 23-7 (34 FR 13078, August 13,
1969), to limit the rule to protection of primary structure from direct effects of lightning.
ix. Reorganization of Subpart D
The FAA proposes relocating the underlying safety intent of various subpart D sections
with proposed sections in subparts B, C, F, and G. The following table shows where the FAA
proposes moving the current subpart D sections in part 23.
Current Section
Proposed
Section
Title
115
Proposed Title
Current Section
23.601
23.603
23.605
23.607
23.609
23.611
Title
23.619
23.621
23.623
23.625
23.627
23.629
General
Materials and workmanship
Fabrication methods
Fasteners
Protection of Structure
Accessibility
Material strength properties
and design values
Special factors
Casting factors
Bearing factors
Fitting factors
Fatigue strength
Flutter
23.641
Proof of strength
23.651
Proof of strength
23.655
Installation
23.657
23.659
23.671
(a)
(b)
Hinges
Mass balance
Control Surfaces - General
--Stability augmentation and
automatic and poweroperated systems
Primary flight controls
Stops
Trim systems
----Control system locks
23.613
23.672
23.673
23.675
23.677
(a)
(b)
(c)
(d)
23.679
Proposed
Section
23.500
23.500
23.510
23.505
23.505
23.505
Structural design
Structural design
Materials and processes
Protection of structure
Protection of structure
Protection of structure
23.510
Materials and processes
23.515
23.515
23.515
23.515
23.405
23.410
Means of
Compliance
Means of
Compliance
Means of
Compliance
23.515
23.315
-23.500
23.1305
Special factors of safety
Special factors of safety
Special factors of safety
Special factors of safety
Structural durability
Aeroelasticity
23.1305
Function and installation
23.1305
23.1305
-23.700
23.700
23.410
23.700
23.1305
Proposed Title
---Special factors of safety
Flight load conditions
-Structural design
Function and installation
23.681(a)
Limit load static tests
23.325(b)
23.681(b)
23.683
23.685(a), (b),
(c)
23.685(d)
Limit load static tests
Operation tests
23.515
23.500(d)
Function and installation
Function and installation
-Flight control systems
Flight control systems
Aeroelasticity
Flight control systems
Function and installation
Component loading
conditions
Special factors of safety
Structural design
Control system details
23.500(d)
Structural design
Control system details
23.1305
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Function and installation
Current Section
Proposed
Section
23.410 and
23.500
Title
23.687
Spring devices
23.689
Cable systems
--
(a)
--
(b)
--
(c)
--
(d)
--
(e)
--
(f)
23.691
(a)
(b)
(c)
(d)
(e)
(f)
-Artificial stall barrier system
-------
23.700
23.325(b),
23.500(d)
23.325(b),
23.500(d)
23.325(b),
23.500(d)
23.325(b),
23.500(d)
23.700
-23.700
23.700
23.1305
23.700
23.700
23.700
(g)
--
23.1315
23.693
23.697
(a)
(b) and (c)
23.699
Joints
Wing flap controls
--Wing flap position indicator
23.515
-23.700
23.200
23.1500
Means Of
Compliance
-23.700
23.700
Definition
23.701
Flap interconnection
23.703
(a)
(b)
(c)
Takeoff warning system
----
23.721
General
23.723
Shock absorption tests
23.725
Limit drop tests
23.726
Ground load dynamic tests
23.910
117
Means Of
Compliance
Means Of
Compliance
Means Of
Proposed Title
Aeroelasticity and Structural
design
Component loading
conditions, Structural design,
and Equipment Systems and
Installations
Flight control systems
Component loading
conditions, Structural design
Component loading
conditions, Structural design
Component loading
conditions, Structural design
Component loading
conditions, Structural design
Flight control systems
-Flight control systems
Flight control systems
Function and installation
Flight control systems
Flight control systems
Flight control systems
Equipment, systems and
Installations
Special factors of safety
-Flight control systems
Controllability
Flightcrew interface
--Flight control systems
Flight control systems
-Powerplant installation
hazard assessment
----
Current Section
23.727
23.729
(a)
(b)
(c)
Title
Reserve energy absorption
drop tests
Landing gear extension and
retraction system
----
Proposed
Section
Compliance
Means Of
Compliance
--
(d)
--
(e)
--
23.705
23.705
23.705
Means Of
Compliance
23.705
(f)
--
23.1315
(g)
--
23.731
23.733
(a)
Wheels
Tires
--
(b)
--
(c)
--
23.735
(a)
Means Of
Compliance
23.705
-23.705
Means Of
Compliance
Means Of
Compliance
23.705
23.705
Means Of
Compliance
Means Of
Compliance
23.705
Means Of
Compliance
Brakes
--
(1)
--
(2)
--
(b)
--
(c)
--
(d)
--
23.1315
(e)
--
(1)
--
(2)
--
23.705
Means Of
Compliance
Means Of
Compliance
23.705
23.1500
--
23.737
23.745
23.751
(a)
Skis
Nose/Tail wheel steering
Main float buoyancy
--
710
118
Proposed Title
--Landing gear systems
Landing gear systems
Landing gear systems
-Landing gear systems
Equipment, systems and
installation --Landing gear systems
-Landing gear systems
---Landing gear systems
--Landing gear systems
-Equipment, systems and
installation
Landing gear systems
--Landing gear systems
Flightcrew interface
-Buoyancy for seaplanes and
amphibians
Current Section
Title
(b)
--
Proposed
Section
Means Of
Compliance
23.753
Main float design
23.320
23.755
Hulls
23.710
23.757
Auxiliary floats
23.710
23.771
(a)
Pilot compartment
--
-23.1500
(b)
--
23.755
(c )
--
23.755
23.773
(a)
(b)
23.775
Pilot compartment view
--
-23.1500
--
23.755
Windshields and windows
--
-Ground and water load
conditions
Buoyancy for seaplanes and
amphibians
Buoyancy for seaplanes and
amphibians
-Flightcrew interface
Occupant physical
environment
Occupant physical
environment
-Flightcrew interface
Occupant physical
environment
-Occupant physical
environment
(a), (b), (c), (d)
--
(e)
--
(f)
--
(g)
--
(h)
--
23.755
23.777
23.1500
23.1500
Flightcrew interface
23.781
23.783
Cockpit controls
Motion and effect of cockpit
controls
Cockpit control knob shape
Doors
Occupant physical
environment
Flightcrew interface
23.1500
--
(a), (b), (c), (d)
--
23.750
Flightcrew interface
-Means of egress and
emergency exits
(e), (f), (g)
--
Means Of
Compliance
23.785
Seats, berths, litters, safety
belts, and shoulder harnesses
23.600 and
23.515
23.779
23.787
23.791
23.755
Proposed Title
Means Of
Compliance
23.1405
Means Of
Compliance
Baggage and cargo
compartments
Passenger information signs
119
23.600(e)
23.755
-Flight in icing conditions
--
-Special factors of safety,
Emergency landing
conditions
Emergency landing
conditions
Occupant physical
Current Section
Proposed
Section
Title
Proposed Title
environment
23.803
Emergency evacuation
--
(a)
--
23.750
(b)
--
Means Of
Compliance
23.805
23.807
(a)(3 ), (b)(1),
(c), (d)(1), (d)(4)
Balance of
23.807
Flightcrew emergency exits
Emergency exits
23.750
-Means Of
Compliance
---
23.750
23.811
Emergency exit marking
23.750
23.812
Emergency lighting
23.750
23.813
Emergency exit access
(a)
--
23.750
(b)
--
Means Of
Compliance
CS-VLA 853
--
23.750
23.815
Width of aisle
23.750
23.831
Ventilation
23.755
23.841(a), (b)(6),
Pressurized cabins
(c) ,(d)
(b)(1) through
-(5) and (7)
23.843
Pressurization tests
23.851
Fire extinguishers
23.755
Means Of
Compliance
23.755
-Means of egress and
emergency exits
-Means of egress and
emergency exits
--Means of egress and
emergency exits
Means of egress and
emergency exits
Means of egress and
emergency exits
-Means of egress and
emergency exits
-Means of egress and
emergency exits
Means of egress and
emergency exits
Occupant physical
environment
Occupant physical
environment
-Occupant physical
environment
-Fire protection outside
designated fire zones
(a) and (b)
--
23.800
(c)
--
Means Of
Compliance
--
--
--
23.853
(a)
Passenger and crew
compartment interiors
--
23.800
120
Fire protection outside
designated fire zones
Current Section
(b)(c) and
(d)(1)(2)
(d)(3)(i),
(d)(3)(iii),
(d)(3)(iv)
Proposed
Section
Means Of
Compliance
Title
---
23.800
(e)
--
23.800
(f)
--
23.800
23.855
23.856
23.859
Cargo and baggage
compartment fire protection
Thermal/acoustic insulation
materials
Combustion heater fire
protection
23.800
23.800
Proposed Title
-Fire protection outside
designated fire zones
Fire protection outside
designated fire zones
Fire protection outside
designated fire zones
Fire protection outside
designated fire zones
Fire protection outside
designated fire zones
-Fire protection outside
designated fire zones
(a)
--
23.800
(b) thru (i)
--
Means Of
Compliance
--
--
--
23.863
Flammable fluid fire
protection
(a) and (d)
--
23.800
(b) and (c)
--
Means Of
Compliance
23.865
23.867
Fire protection of flight
controls, engine mounts, and
other flight structure
Electrical bonding and
protection against lightning
and static electricity
23.805
Fire protection in designated
fire zones
--
--
(a), (c)
--
23.810
(b)
--
23.1320
23.871
Means Of
Compliance
Leveling means
121
Fire protection outside
designated fire zones
Fire protection outside
designated fire zones
Lightning protection of
structure
Electrical and electronic
system lightning protection
--
5. Subpart E – Powerplant
a. General Discussion
The FAA proposes substantial changes to subpart E based on two considerations. First,
many of the current regulations could be combined to provide fewer regulations that accomplish
the same safety intent. Second, part 23 overlaps with the requirements in parts 33 and 35. Refer
to appendix 1 of this preamble for a cross-reference table detailing how the current regulations
are addressed in the proposed part 23 regulations.
b. Specific Discussion of Changes
i. Proposed § 23.900, Powerplant Installation
Proposed § 23.900 would clarify, for the purpose of this subpart, that the airplane
powerplant installation must include each component necessary for propulsion, affects
propulsion safety, or provides auxiliary power to the airplane. Proposed § 23.900 would require
the applicant to construct and arrange each powerplant installation to account for likely hazards
in operation and maintenance and, except for simple airplanes24, each aircraft engine would have
to be type certificated.
Proposed § 23.900 would capture the safety intent of current §§ 23.901, Installation,
paragraphs (a), (b), and (f); 23.903, Engines, paragraph (a); 23.905, Propellers, paragraph (a),
23.909, Turbocharger systems, paragraphs (a) and (c); and 23.925, Propeller clearance. Proposed
§ 23.900 would combine the installation requirements that are scattered throughout the subpart
into a general requirement for installation, and remove any duplication with part 33. The
following table illustrates the duplication between the current part 23 regulations and part 33
requirements:
24
Refer to Section III, Discussion of Proposal, paragraphs A and B of this NPRM for definition and discussion of a
simple airplane.
122
Part 23
§ 23.901(d), Installation
§ 23.901(e), Installation
§ 23.934, Turbojet and turbofan engine
thrust reverser systems tests
§ 23.939, Powerplant operating
characteristics
§ 23.1011, Oil System – General
Part 33
§ 33.33, Vibration
§ 33.1, Applicability
§ 33.97, Thrust reversers
§§ 33.61 thru -33.79
§§ 33.39 and 33.71, Lubrication system
§§ 33.39, and 33.71, Lubrication
system
§ 33.33, Vibration
§ 33.33, Vibration
§ 33.1, Applicability
§§ 33.41 and 33.81, Applicability –
Block Tests
§ 23.1013(a) and (d), Oil tanks
§ 23.1015, Oil tank tests
§ 23.1023, Oil radiators
§ 23.1041, Cooling—General
§ 23.1043, Cooling tests
§ 23.1045, Cooling test procedures for
turbine engine powered airplanes
§ 23.1047, Cooling test procedures for
reciprocating engine powered airplanes
§ 23.1061, Liquid Cooling—
§Installation
23.1063, Coolant tank tests
§ 23.1093, Induction system icing
protection
§ 23.1099, Carburetor deicing fluid
system detail design
§ 33.81, Applicability – Block Tests
§ 33.35, Fuel and induction system
§ 33.21, Engine cooling
§ 33.41 and 33.81, Applicability –
Block
Tests Fuel and induction system
§§
33.35(b),
and 33.68, Induction system icing
§ 33.35, Fuel and induction system
Additionally, proposed § 23.900 would identify the scope of the powerplant installation
in the same manner as the current requirements. However, the FAA would redefine several terms
to allow for alternate sources of propulsion, such as electric motors. The FAA considers the term
powerplant to include all equipment used by the airplane that provides propulsion or auxiliary
power. The word engine would be replaced with the term power unit and would include other
power sources driven by fuel such as liquid fuel, electrical, or other power sources not yet
envisioned. This proposal also predicates that each airplane power unit or propeller receive a
type certificate as a prerequisite for installation, with the exception of simple airplanes. The
current part 33 airworthiness standards did not envision providing certification requirements for
types of engines outside of those that operate on fossil fuels. As such, the ability of an applicant
123
to obtain the required engine type certificate for an alternate fuel type may be impractical. For
those power units, the FAA proposes to include them in the airplane certification, which could
include the use of an ELOS to part 23. The FAA would expect an applicant to utilize all the
requirements listed in part 33 as a baseline matrix to find compliance for an alternate powerplant
type and for those requirements that could not be met. Also, § 21.16, Special conditions, may
apply. It should be noted that additional requirements might also be necessary due to an absence
of a corresponding part 33 requirement. This matrix would become part of the certification
baseline and recorded in an issue paper as an ELOS, exemption, or special condition. Also,
simple airplanes will follow the precedence set for CS-VLA and will maintain the exception to
the requirement to be type certificated.
ii. Proposed § 23.905, Propeller Installation
Proposed § 23.905 would retain the requirement that each propeller be type certificated,
except for simple airplanes. Proposed § 23.905 would retain the requirement that each pusher
propeller be marked so that it is conspicuous under daylight conditions. All the other
requirements of the current section either duplicate part 35 standards, or would condense into the
other requirements proposed in §§ 23.900, Powerplant installation; 23.910, Powerplant
installation hazard assessment; and 23.940, Powerplant ice protection.
iii. Proposed § 23.910, Powerplant Installation Hazard Assessment
Proposed § 23.910 would require an applicant to assess each powerplant separately and in
relation to other airplane systems and installations to show that a failure of any powerplant
system component or accessory will not—

Prevent continued safe flight and landing;

Cause serious injury; and
124

Require immediate action by crewmembers for continued operation of any
remaining powerplant system.
Proposed § 23.910 would capture the safety intent of current §§ 23.721, Landing gear—
General; 23.903, Engines, paragraph (c); 23.905, Propellers, paragraph (h); 23.909, Turbocharger
systems, paragraph (b),(c), and (e); 23.933 Reversing systems, paragraph (b); 23.937,
Turbopropeller-drag limiting systems, paragraph (a); 23.959, Unusable fuel supply; 23.979,
Pressure fueling systems, paragraphs (c) and (d); 23.991, Fuel pumps, paragraph (d); 23.994,
Fuel system components; 23.1001, Fuel jettisoning system, paragraph (h); 23.1027, Propeller
feathering system; 23.1111, Turbine engine, paragraph (a) and (c); 23.1123, Exhaust system;
23.1125 Exhaust heat exchangers, paragraph (a); 23.1142, Auxiliary power unit controls,
paragraphs (d) and (e); 23.1155, Turbine engine reverse thrust and propeller pitch settings below
the flight regime; 23.1163, Powerplant accessories, paragraphs (b) and (d); 23.1191, Firewalls,
paragraph (f); 23.1193, Cowling and nacelle, paragraphs (f) and (g); 23.1201, Fire extinguishing
systems materials, paragraph (a); and 23.1203, Fire detector system, paragraphs (b) and (c).
The proposed standard would reduce the repetitive requirements found throughout the
subpart and create one general powerplant requirement to analyze and mitigate hazards
associated with the powerplant installation. For example, current § 23.903(b)(1) requires that
design precautions be taken to minimize the hazards to the airplane in the event of an engine
rotor failure or a fire originating inside the engine that could burn though the engine case. These
are very specific failure conditions, but are actually only two small categories of many engine
failure conditions an applicant must assess. Section 23.903(c) requires that multiple engines must
be isolated from one another so a malfunction of one engine does not affect the operation of the
other. This is a general analysis technique frequently called common mode analysis that should
125
apply to all powerplant components and include other critical airplane systems that are not
powerplant related, but could be affected by a powerplant failure. Hazards the FAA proposes to
remove from other regulations and which would be addressed in this proposed section include,
but are not limited to, fire, ice, rain and bird ingestion, rotorburst, engine case burn through, and
flammable leakage.
iv. Proposed § 23.915, Automatic Power Control Systems
Proposed § 23.915 would require a power or thrust augmentation system that
automatically controls the power or thrust on the operating powerplant to provide an indication
to the flightcrew when the system is operating; provide a means for the pilot to deactivate the
automatic functions; and prevent inadvertent deactivation.
Proposed § 23.915 would capture the safety intent of current § 23.904, Automatic power
reserve system and appendix H to part 23—Installation of An Automatic Power Reserve (APR)
System. To foster the growth and approval of technological advances, the FAA believes that the
detailed and prescriptive language of appendix H is more appropriate as means of compliance.
We would also include requirements for thrust augmenting systems into this proposed section
since there seems to be a trend in general aviation to provide thrust management systems more
sophisticated than historical automatic power reserve systems.
v. Proposed § 23.920, Reversing Systems
Proposed § 23.920 would require an airplane to be capable of continued safe flight and
landing under any available reversing system setting, and would capture the safety intent of
current § 23.933(a) and (b). The current rule includes a separate requirement for a propeller
reversing system that would be covered in the more general language of the proposed section and
applied to any type of reverser system. Current § 23.933 also requires an analysis of the system
126
for a failure condition. Those provisions would be addressed in the general analysis requirements
of proposed § 23.910.
vi. Proposed § 23.925, Powerplant Operational Characteristics
Proposed § 23.925 would require the powerplant to operate at any negative acceleration
that could occur during normal and emergency operation within the airplane operating
limitations. Proposed § 23.925 would require the pilot to have the capability to stop and restart
the powerplant in flight. Proposed § 23.925 would require the airplane to have an independent
power source for restarting each powerplant following an in-flight shutdown.
Proposed § 23.925 would capture the safety intent of current §§ 23.903, Engines,
paragraph (d), (e), (f), and (g); 23.939, Powerplant operating characteristics; and 23.943,
Negative acceleration. Current § 23.939 addresses powerplant operating characteristics and
clearly requires an analysis that would be required by proposed § 23.910 and the existing
requirements of part 33. Current § 23.943 would be included in this proposed rule because it is
another analysis requirement, and one that provides an environment where powerplant systems
are required to operate.
vii. Proposed § 23.930, Fuel Systems
Proposed § 23.930 would require that each fuel system provide an independent fuel
supply to each powerplant in at least one configuration and prevent ignition from an unknown
source. This section would require that each fuel system provide the fuel required to achieve
maximum power or thrust plus a margin for likely variables in all temperature conditions within
the operating envelope of the airplane and provide a means to remove the fuel from the airplane.
Proposed § 23.930 would require each fuel system to be capable of retaining fuel when subject to
127
inertia loads under expected operating conditions and prevent hazardous contamination of the
fuel supply.
Proposed § 23.930 would require each fuel storage system to withstand the loads and
pressures under expected operating conditions and provide a means to prevent loss of fuel during
any maneuver under operating conditions for which certification is requested. Also, proposed
§ 23.930 would require each fuel storage system to prevent discharge when transferring fuel,
provide fuel for at least one-half hour of operation at maximum continuous power or thrust, and
be capable of jettisoning fuel, if required for landing.
Proposed § 23.930 would require installed pressure refueling systems to have a means to
prevent the escape of hazardous quantities of fuel, automatically shut-off before exceeding the
maximum fuel quantity of the airplane, and provide an indication of a failure at the fueling
station. Proposed § 23.930 would capture the safety intent of current §§ 23.951, Fuel System—
General, paragraphs (a), (b), (c), and (d); 23.953, Fuel System; 23.954, Fuel system lightning
protection; 23.955, Fuel flow; 23.957, Flow between interconnected tanks, paragraph (a); 23.961,
Fuel system hot weather operation; 23.963, Fuel tanks: General, paragraphs (a), (d), and (e);
23.977, Fuel tank outlet; 23.979, Pressure fueling systems, paragraphs (a) and (b); 23.991, Fuel
pumps, paragraphs (a), (b), and (c); 23.997, Fuel strainer or filter, paragraphs (a), (b), (c), and
(d); 23.999, Fuel system drains; and 23.1001, Fuel jettisoning system, paragraph (a).
The FAA believes that the regulations for the design of fuel systems may be overly
prescriptive and exceed what is necessary to design a safe system. Accordingly, a more general
set of requirements could include the intent of many current rules. More importantly, this
proposed rule would allow for other types of energy sources to power propulsion systems such as
electrical motors and future energy sources.
128
viii. Proposed § 23.935, Powerplant Induction and Exhaust Systems
Proposed § 23.935 would require the air induction system to supply the air required for
each power unit and its accessories under expected operating conditions, and provide a means to
discharge potential harmful material. Proposed § 23.935 would capture the safety intent of
current §§ 23.1091, Air induction system, paragraph (a); 23.1101, Induction air preheater design,
paragraph (a); 23.1103, Induction system ducts; 23.1107, Induction system filters; and 23.1121,
Exhaust System—General, paragraphs (a) through(g). This proposed rule would combine
induction and exhaust systems into a single rule because of the commonality with issues
associated with moving air. The prescriptive language of the regulations identified above in this
paragraph drove the development of this proposed section. For example, § 23.1091(b) mandates
a certain number of intake sources and specifies particular requirements for a primary and
alternate intakes. Current § 23.1101 requires inspection access of critical parts, and current
§ 23.1103 is considered a part of a proper safety analysis that would be required by proposed
§ 23.910.
ix. Proposed § 23.940, Powerplant Ice Protection
Proposed § 23.940 would require the airplane design, including the engine induction
system, to prevent foreseeable accumulation of ice or snow that would adversely affect
powerplant operation. Proposed § 23.940 would also require the applicant design the powerplant
to prevent any accumulation of ice or snow that would adversely affect powerplant operation, in
those icing conditions for which certification is requested. Proposed § 23.940 would capture the
safety intent of current §§ 23.905, Propellers, paragraph (e); 23.929, Engine installation ice
protection; 23.975, Fuel tank vents and carburetor vapor vents, paragraph (a)(1); 23.1093,
Induction system icing protection; 23.1095, Carburetor deicing fluid flow rate; 23.1097,
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Carburetor deicing fluid system capacity; and 23.1099, Carburetor deicing fluid system detail
design.
Proposed § 23.940(a) would reflect the requirements in current § 23.1093, which applies
to all airplanes, regardless if flight in icing certification is sought. We are proposing to remove
the type of powerplant to accommodate for new powerplant technologies. In addition, we
propose to define other foreseeable icing in the means of compliance, which would include
conditions conducive to induction icing of reciprocating engines. Foreseeable icing in the means
of compliance would also include the cloud icing conditions of appendix C to part 25, currently
defined in § 23.1093(b)(1)(i), falling and blowing snow currently defined in § 23.1093(b)(1)(ii),
and ground ice fog conditions currently defined in § 23.1093(b)(2). The FAA proposes to
remove the prescriptive requirements of the current §§ 23.1093(a), 23.1095, 23.1097, and
23.1099 as these are more appropriately considered as means of compliance. The FAA would
expect the means of compliance to expand the ground ice fog conditions to colder ambient
temperatures to harmonize with EASA. The FAA would also expect the means of compliance to
include optional ground and flight freezing drizzle and freezing rain conditions, similar to
appendix O of part 25, for those airplanes that seek certification to operate in those conditions.
The Part 23 Icing ARC had recommended specific pass/fail criteria for the effect of ice accretion
on engine operation. The FAA would expect this criterion to be defined in a means of
compliance. Proposed paragraph (a) would require an airplane design to prevent “foreseeable”
ice or snow accumulation, including accumulation in inadvertent icing encounters, described in
appendix C to part 25, on airplanes not certified for icing, which may pose a shed hazard to the
powerplant.
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Airplane design in proposed § 23.940(a) refers to the engine induction system and
airframe components on which accumulated ice may shed into the powerplant. Powerplant
design in proposed § 23.940(b) refers to the engine, propeller, and other powerplant components
such as cooling inlets.
Proposed § 23.940(b) would apply only to airplanes certified for flight in icing and would
require compliance to the icing requirements in part 33, which currently only apply to turbine
engines. Part 33, amendment 33-34 (79 FR 65507, November 4, 2014) and effective January 5,
2015, added SLD and ice crystal requirements to § 33.68 and amended the engine ice ingestion
requirements in § 33.77. Proposed § 23.940(b) would require installation of an engine(s) certified
to § 33.68 amendment 33-34, or later, if the airplane will be certified for flight in freezing drizzle
and freezing rain. Proposed § 23.940(b) would allow an airplane manufacturer to install an
engine, type certified at an earlier amendment, in an airplane not certified for flight in freezing
drizzle or freezing rain, as long as no ADs have been applied that relate to engine operation in
inadvertent SLD or ice crystal conditions. Airplanes certified under part 23 have not had ADs
related to SLD or ice crystals. Certain part 23 turbojet engines have experienced thrust rollback
due to ice crystals blocking the heated inlet temperature probe. The FAA would expect the
means of compliance to address this in a similar manner to what is accomplished on current
certification projects. The engine ice ingestion requirements of the current § 23.903(a)(2) would
be moved to proposed § 23.940(b).
x. Proposed § 23.1000, Powerplant Fire Protection
Proposed § 23.1000 would require that a powerplant only be installed in a designated fire
zone and would require an applicant to install a fire detection system in each designated fire zone
for certification levels 3 and 4 airplanes. This rulemaking effort is maintaining the current level
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of safety for fire protection. While not a perfect one-to-one relationship, airplanes equivalent to
certification levels 1 and 2 airplanes are not required to have a fire detection system today and
therefore, should not be required to have them in this proposed rule. This would increase the cost
of certification. Each fire detection system would be required to provide a means to alert the
flightcrew in the event of a detection of fire or failure of the system and a means to check the fire
detection system in flight. Proposed § 23.1000 would also require an applicant to install a fire
extinguishing system for certification levels 2, 3, and 4 airplanes with a powerplant located
outside the pilot’s view that uses combustible fuel.
Additionally, proposed § 23.1000 would require each component, line, and fitting
carrying flammable fluids, gases, or air subject to fire conditions to be fire resistant, except
components storing concentrated flammable material would have to be fireproof or enclosed by a
fireproof shield. Proposed § 23.1000 would also require an applicant to provide a means to shut
off fuel or flammable material for each powerplant, while not restricting fuel to remaining units,
and prevent inadvertent operation. Proposed § 23.1000 would capture the safety intent of current
§§ 23.1181, Designated fire zones: regions included; 23.1182, Nacelle areas behind firewalls;
23.1183, Lines, fittings, and components; 23.1189, Shutoff means; 23.1191, Firewalls; 23.1192
Engine accessory compartment diaphragm; 23.1193, Cowling and nacelle; 23.1195, Fire
extinguishing systems; 23.1197, Fire extinguishing agents; 23.1199, Extinguishing agent
containers; 23.1201, Fire extinguishing system materials; and 23.1203, Fire detector system.
Regulations for fuel may have become too detailed and prescriptive. A more general set
of requirements should capture the intent of these many rules. More importantly, this new
proposed rule would allow other types of energy sources to power propulsion systems such as
electrical motors and future energy sources.
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xi. Current Subpart E Regulations Relocated to Other Proposed Subparts
The requirements of current § 23.903(b)(1) would be moved to subpart C, § 23.405,
Structural durability, paragraph (d). Section 23.903(b)(1) requires design precautions for turbine
engine installations to be taken to minimize hazards to the airplane in the event of an engine
rotor failure or of a fire originating inside the engine which burns through the engine case.
Additionally, the requirements of current § 23.929 would be moved to proposed
§ 23.940(b) and would only apply to airplanes certified for flight in icing. The means of
compliance for § 23.940(b) should address propeller ice protection system design and analysis.
However, the means of compliance for climb performance for proposed § 23.230 should address
ice accretion effects on propeller performance on airplanes certified for flight in icing.
xii. Removal of Subpart E Current Regulations
The following current regulations are considered duplicative of part 35 and would be
removed from subpart E: § 23.905(b) - duplicative of § 35.5, Propeller ratings and operation
limitations; § 23.905(c) - duplicative of § 35.22, Feathering propellers; § 23.905(d) - duplicative
of §§ 35.21, 35.23, 35.42 and 35.43; and § 23.905(e)(g) and (h) - duplicative of § 35.7, Features
and characteristics.
6. Subpart F – Equipment
a. General Discussion
The proposed changes to subpart F would consolidate the current rules into new
performance-based standards and allow for use of new technologies once consensus standards
are developed that could be used as a means of compliance.The FAA believes the proposed part
23 requirements would maintain the current level of safety while staying relevant for new future
technologies. The prescriptive design solutions in the current rules are often not relevant to new
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technology requiring special conditions, exemptions, and ELOS findings. The rate of new
technology development and adoption has increased dramatically in the last decade. As a result,
airplane systems with new features and capabilities are rapidly becoming available. The FAA
believes that removing the prescriptive design solutions, which are based on outdated or existing
technology, while focusing on the safety intent of the rule and maintaining design solutions as a
documented means of compliance would enable the adoption of newer technologies.
The FAA also believes the current part 23 regulatory prescriptive structure does not
effectively address the safety continuum, particularly the low performance end of the continuum.
Recent part 23 amendments have increasingly focused on high-performance, complex airplanes.
These stricter requirements have also been applied to the low-performance airplanes even
though their risk in the safety continuum is lower. This has created an unintended barrier to new
safety enhancing technology in low-performance airplanes.
b. Specific Discussion of Changes
i. Proposed § 23.1300, Airplane Level Systems Requirements
Proposed § 23.1300 would require equipment and systems that are required for an
airplane to operate safely, be designed and installed to meet the level of safety applicable to the
certification and performance levels of the airplane, and to perform their intended function
throughout the operating and environmental limits specified by an applicant. Proposed § 23.1300
would mandate that non‐required airplane equipment and systems, considered separately and in
relation to other systems, be designed and installed so their operation or failure would not have
an adverse effect on the airplane or its occupants.
Proposed § 23.1300 would capture the safety intent found in portions of current
§§ 23.1301, Function and installation; 23.1303, Flight and navigation instruments; 23.1305,
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Powerplant instruments; 23.1307, Miscellaneous equipment; 23.1309, Equipment, systems, and
installations; 23.1311, Electronic display instrument systems; 23.1321, Arrangement and
visibility; 23.1323, Airspeed indicating system, 23.1325, Static pressure system; 23.1327,
Magnetic direction indicator; 23.1329, Automatic pilot system; 23.1335, Flight director systems;
23.1337, Powerplant instruments installation; 23.1351, Electrical Systems and Equipment—
General; 23.1353, Storage battery design and installation; and 23.1361, Master switch
arrangement.
The current requirements can be traced back to CAR 3, specifically CAR 3.651, 3.652,
3.655, 3.661, 3.662, 3.663, 3.665, 3.666, 3.667, 3.669, 3.670, 3.671, 3.672, 3.673, 3.674, 3.681,
3.682, 3.686, 3.687, and 3.683. These requirements, including § 23.1311, which does not have a
corresponding rule in CAR 3, were based on the technology and design solutions available at the
time of their adoption. Although these requirements are appropriate for traditional systems found
in airplanes designed to these assumptions, they lack the flexibility to adopt current and
anticipated technologies and design capabilities. The FAA wants to facilitate the use of systems
in new airplanes that reduce pilot workload and enhance safety. The FAA proposes the use of
performance-based language that maintains the level of safety achieved with the current
requirements for traditionally designed airplanes but also allows for alternative system designs in
the future.
Proposed § 23.1300(a) would address equipment and systems required to operate safely.
Required equipment may be defined by other parts such as part 91 or part 135, by other sections
of this part such as equipment necessary for flight into known icing, or other requirements placed
on the Type Certificate Data Sheet (TCDS) such as a working autopilot for single pilot
operations. The FAA proposes in § 23.1300(b) that non-required equipment may be installed
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because it offers some benefit and its failure or use would not result in a reduction in safety of
the airplane or for its occupants from the base aircraft if the system was not installed. This
proposed section would contain general requirements for the environmental qualifications of
installed equipment, and would require installed equipment to perform its intended function over
its defined environmental range. This would mean that the equipment should have the same
environmental qualification as requested for the useful range of the airplane.
Proposed § 23.1300(b) would not mandate that non-required equipment and systems
function properly during all airplane operations once in service, provided all potential failure
conditions do not effect safe operation of the airplane. The equipment or system would have to
function in the manner expected by the manufacturer’s operating manual for the equipment or
system. An applicant’s statement of intended function would have to be sufficiently specific and
detailed so that the FAA could evaluate whether the system was appropriate for the intended
function.
ii. Proposed § 23.1305, Function and Installation
Proposed § 23.1305 would require that each item of installed equipment perform its
intended function, be installed according to limitations specified for that equipment, and the
equipment be labeled, if applicable, due to size, location, or lack of clarity as to its intended
function, as to its identification, function or operating limitations, or any combination of these
factors. Proposed § 23.1305 would require a discernable means of providing system operating
parameters required to operate the airplane, including warnings, cautions, and normal indications
to the responsible crewmember. Proposed § 23.1305 would require information concerning an
unsafe system operating condition be provided in a clear and timely manner to the crewmember
responsible for taking corrective action.
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Proposed § 23.1305 would capture the safety intent found in portions of the current
§§ 23.671,Control systems-General; 23.672, Stability augmentation and automatic and poweroperated systems; 23.673, Primary flight controls; 23.675, Stops; 23.679, Control system locks;
23.685(d),Control system details; 23.691(c), Artificial stall barrier system; 23.1361, Master
switch arrangement; and 23.1365(a)and (b), Electric cables and equipment; 23.1301, Function
and installation; 23.1303, Flight and navigation instruments; 23.1305, Powerplant instruments;
23.1309, Equipment, systems, and installations; 23.1322, Warning, caution, and advisory lights;
23.1323, Airspeed indicating system; 23.1326, Pitot heat indication systems; 23.1327, Magnetic
direction indicator; 23.1329, Automatic pilot system; 23.1331, Instruments using a power source;
23.1335, Flight director systems; 23.1337, Powerplant instruments installation; 23.1351,
Electrical Systems and Equipment—General; 23.1353, Storage battery design and installation;
23.1365, Electric cables and equipment; 23.1367, Switches; 23.1416, Pneumatic de-icer boot
system. The current requirements can be traced to CAR 3, specifically, CAR 3.651, 3.652, 3.655,
3.663, 3.666, 3.667, 3.668, 3.669, 3.670, 3.671, 3.672, 3.673, 3.674, 3.675, 3.681, 3.682, 3.683,
3.686, 3.687, 3.693, 3.694, 3.696, 3.697, 3.700, 3.712, and 3.726. These requirements, including
§§ 23.1322, 23.1326, and 23.1441, which did not have corresponding rules in CAR 3, were
based on the technology and design solutions available at the time of their adoption. Although
these requirements are appropriate for traditional systems and designs found in airplanes
designed to these assumptions, they lack the flexibility to adopt current and anticipated
technologies and design capabilities. The FAA wants to facilitate the use of systems in new
airplanes that reduce pilot workload and enhance safety. The FAA proposes the use of
performance-based language that maintains the safety requirements for traditionally designed
airplanes, but also allows for alternative system designs.
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The equipment or system would have to function in the manner expected by the
manufacturer’s operating manual for the equipment or system. An applicant’s statement of
intended function would have to be sufficiently specific and detailed so that the FAA could
evaluate whether the system was appropriate for the intended function. The equipment should
function when installed as intended by the manufacturer’s instructions. The intent is for an
applicant to define proper functionality and to propose an acceptable means of compliance.
Proposed § 23.1305(a) would require that equipment be installed under prescribed
limitations. Therefore, if an equipment manufacturer specified any allowable installation
requirements, the installer would stay within the limitations or substantiate the new limits. The
proposed requirement that the equipment be labeled as to its identification, function or operating
limitations, or any combination of these factors, if applicable, would apply to the manufacturer
of the equipment, not to the installer.
Proposed § 23.1305 would require that information concerning an unsafe system
operating condition be provided to the flightcrew. Microprocessing units that monitor parameters
and warn of system problems have already been incorporated in some airplanes and are used by
other industries, including the automobile and nuclear energy fields. Pilots may not monitor
gauges as they used to; instead, they could rely on warnings and alerts. The FAA does not
propose to allow simple on-off failure lights to replace critical trend displays. Warning systems
would need to be sophisticated enough to read transients and trends, when appropriate, and give
useful warning to the flightcrew.
iii. Proposed § 23.1310, Flight, Navigation, and Powerplant Instruments
Proposed § 23.1310 would require installed systems to provide the flightcrew member
who sets or monitors flight parameters for the flight, navigation, and powerplant information
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necessary to do so during each phase of flight. Proposed § 23.1310 would require this
information include parameters and trends, as needed for normal, abnormal, and emergency
operation, and limitations, unless an applicant showed the limitation would not be exceeded in all
intended operations. Proposed § 23.1310 would prohibit indication systems that integrate the
display of flight or powerplant parameters to operate the airplane or are required by the operating
rules of this chapter, from inhibiting the primary display of flight or powerplant parameters
needed by any flightcrew member in any normal mode of operation. Proposed § 23.1310 would
require these indication systems be designed and installed so information essential for continued
safe flight and landing would be available to the flightcrew in a timely manner after any single
failure or probable combination of failures.
Proposed § 23.1310 would capture the safety intent of current §§ 23.1303, Flight and
navigation instruments; 23.1305, Powerplant instruments; 23.1307, Miscellaneous equipment;
23.1311, Electronic display instrument systems; 23.1321, Arrangement and visibility; 23.1323,
Airspeed indicating system; 23.1331, Instruments using a power source; and 23.1337,
Powerplant instruments installation. The current requirements can be traced to CAR 3,
specifically, CAR 3.655, 3.661, 3.662, 3.675, 3.663, 3.668, 3.670, 3.671, 3.672, 3.673, and
3.674. These requirements, including § 23.1311, which did not have a corresponding rule in
CAR 3, were based on the technology and design solutions available at the time of their
adoption. Although these requirements are appropriate for traditional systems and designs found
in airplanes designed to these assumptions, they lack the flexibility to adopt current and
anticipated technologies and design capabilities. Furthermore, the FAA proposes to remove
prescriptive requirements from the rule that historically provided standardization for primary
flight instruments and controls. The FAA still believes this standardization is important for
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traditionally designed airplane instrumentation. Accordingly, to reduce the potential for pilot
error, the reliance on standards accepted by the Administrator would maintain standardization
for traditional systems.
The proposed regulations would require applicants to use a means of compliance based
on consensus standards or other means accepted by the Administrator. However, new technology
is already being approved that does not meet the traditional installation requirements and
guidance. At the same time, this technology is proving equivalent or better than the traditional
technology25. Furthermore, the FAA believes that new systems, displays, and controls have the
potential to reduce pilot workload with a direct safety benefit. By removing prescriptive
requirements for the rules and allowing alternatives, the industry would be able to develop and
certify safety-enhancing technology faster.
Proposed § 23.1310 would not require limitations that could not be exceeded due to
system design or physical properties to be shown because they would be useless information and
result in clutter of the displays. Additionally, the FAA proposes removing the prescriptive design
requirement in current § 23.1311 for the installation of secondary indicators. The safety intent is
that a single failure or likely multiple failures would not result in the lack of all critical flight
data. The design and installation of flight critical information should be such that the pilot could
still fly partial panel after probable failures. The prescriptive redundancy requirements for
installed secondary indicators have been too restrictive for airplanes limited to VFR operations.
This has caused several applicants to request an ELOS finding from current § 23.1311(a)(5).
The safety intent of § 23.1311 is to provide crewmembers the ability to obtain the
information necessary to operate the airplane safely in flight. Traditionally, the minimum was
25
See Accident and GA Safety reports from NTSB, AOPA Safety Foundation, and the General Aviation Joint
Steering Committee (GA-JSC) over the past 10 years.
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prescribed as airspeed, altimeter, and magnetic direction. The corresponding CAR 3 rule is
3.655. The regulation is redundant with the operating rules, specifically, §§ 91.205 and 135.149,
as well as providing prescriptive design solutions that were assumed to achieve an acceptable
level of safety. The prescriptive solutions precluded finding more effective or more economical
paths to providing acceptable safety. Proposed § 23.1310 would maintain the safety intent of the
current rule.
The FAA proposes consolidating the safety intent of current § 23.1305, Powerplant
instruments, into proposed § 23.1310, Flight, Navigation, and Powerplant Instruments. The
safety intent of § 23.1305 is to provide crewmembers the ability to obtain the information
necessary to operate the airplane and powerplant safely in flight. Traditionally, the minimum was
prescribed, such as oil pressure, oil temperature, and oil quantity for all airplanes. The
corresponding rules in CAR 3 are 3.655 and 3.675. Some of the regulation was redundant with
the operating rules as well as providing prescriptive design solutions that were assumed to
achieve an acceptable level of safety based on an assumption of powerplant types. The
prescriptive solutions precluded finding more effective or more economical paths to providing
acceptable safety. Additionally, they do not facilitate adoption of new technologies such as
electric powered airplanes. The proposed § 23.1310, Flight, Navigation, and Powerplant
Instruments, would maintain the safety intent of the current rule.
iv. Proposed § 23.1315, Equipment, Systems, and Installation
Proposed § 23.1315 would require an applicant to examine the design and installation of
airplane systems and equipment, separately and in relation to other airplane systems and
equipment, for any airplane system or equipment whose failure or abnormal operation has not
been specifically addressed by another requirement in this part. Proposed § 23.1315 would
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require an applicant to determine if a failure of these systems and equipment would prevent
continued safe flight and landing and if any other failure would significantly reduce the
capability of the airplane or the ability of the flightcrew to cope with adverse operating
conditions. Proposed § 23.1315 would require an applicant to design and install these systems
and equipment, examined separately and in relation to other airplane systems and equipment,
such that each catastrophic failure condition is extremely improbable, each hazardous failure
condition is extremely remote, and each major failure condition was remote. Proposed § 23.1315
would capture the safety intent found in portions of current §§ 23.691(g), Artificial stall barrier
system; 23.729(f), Landing gear extension and retraction system; 23.735(d), Brakes; 23.1309,
Equipment, systems, and installations; 23.1323, Airspeed indicating system; 23.1325, Static
pressure system; 23.1329, Automatic pilot system; 23.1331, Instruments using a power source;
23.1337, Powerplant instruments installation; 23.1335, Flight director systems; 23.1353, Storage
battery design and installation, 23.1357, Circuit protective devices; 23.1431, Electronic
equipment; 23.1441(b), Oxygen equipment and supply; 23.1450(b), Chemical oxygen
generators; 23.1451, Fire protection for oxygen equipment; and 23.1453, Protection of oxygen
equipment from rupture. The current requirements can be traced to CAR 3, specifically, 3.652,
3.663, 3.665, 3.667, 3.668, 3.670, 3.671, 3.672, 3.673, 3.674, and 3.683. The foundation of the
current § 23.1309 was derived from CAR 3.652, which stated that “each item of equipment,
which is essential to the safe operation of the airplane, shall be found by the Administrator to
perform adequately the functions for which it is to be used...”. At that time, the airworthiness
requirements were based on single-fault or fail-safe concepts. Due to the increased use of
airplanes certificated under part 23 in the 1970s for all-weather operation, and a pilot’s increased
reliance on installed avionic systems and equipment, § 23.1309, amendment 23-14
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(38 FR 31816, November 19, 1973), was issued to provide an acceptable level of safety for such
equipment, systems, and installations. Section 23.1309 introduced two main concepts: multiple
failure combinations as well as a single failure had to be considered and there must be an inverse
relationship between the likelihood of occurrence and the severity of consequences. The premise
was that more severe consequences should happen less often.
In addition to specific part 23 design requirements, proposed § 23.1315 requirements
would apply to any equipment or system installed in the airplane. This proposed section
addresses general requirements and is not intended to supersede any specific requirements
contained in other part 23 sections. Proposed § 23.1315 would not apply to the performance or
flight characteristics requirements of subpart B, and structural loads and strength requirements of
subpart C and D. However, it would apply to systems that complied with subpart B, C, D, and E
requirements. As an example, proposed § 23.1315 would not apply to an airplane’s inherent stall
characteristics, but would apply to a stick pusher system installed to attain stall compliance. Both
current § 23.1309 and proposed § 23.1315 rules are not intended to add requirements to specific
rules in part 23, but to account for the added complexity of integration and new technologies.
This proposed regulation would require an engineering safety analysis to identify
possible failures, interactions, and consequences, and would require an inverse relationship
between the probability of failures and the severity of consequences. This would be
accomplished by requiring all of the airplane’s systems to be reviewed to determine if the
airplane was dependent upon a system function for continued safe flight and landing and if a
failure of any system on the airplane would significantly reduce the ability of the flightcrew to
cope with the adverse operating condition. If the design of the airplane included systems that
performed such functions, the systems would be required to meet standards that establish that
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maximum allowable probability of that failure. Section 23.1315 would impose qualitative, rather
than quantitative probabilities of occurrence. As the FAA determined which quantitative values
satisfied the proposed performance standards, it would share that information in FAA guidance
or documented means of compliance appropriate to the certification levels of proposed § 23.5.
v. Proposed § 23.1320, Electrical and Electronic System Lightning Protection
Proposed § 23.1320 would require, for an airplane approved for IFR operations, that each
electrical or electronic system that performed a function, the failure of which would prevent the
continued safe flight and landing of the airplane, be designed and installed such that the airplane
level function continues to perform during and after the time the airplane is exposed to lightning.
Proposed § 23.1320 would also require these systems automatically recover normal operation of
that function in a timely manner after the airplane is exposed to lightning, unless the system’s
recovery conflicts with other operational or functional requirements of the system.
Proposed § 23.1320 would require each electrical and electronic system that performed a
function, the failure of which would reduce the capability of the airplane or the ability of the
flightcrew to respond to an adverse operating condition, be designed and installed such that the
function recovers normal operation in a timely manner after the airplane is exposed to lightning.
Proposed § 23.1320 would capture the safety intent of current § 23.1306, Electrical and
electronic system lightning protection. The original adoption of the rule, first introduced as part
of § 23.1309, was justified because there was an increased use of small airplanes in all-weather
operations with an increasing reliance on complex systems and equipment in the modern,
complex, high-performance airplanes.
The FAA wants to facilitate the use of systems in new airplanes that reduce pilot
workload and enhance safety. The current requirement that all aircraft regardless of their design
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or operational limitations meet the same requirements for lightning regardless of the potential
threat has been burdensome for the traditional VFR-only airplane designs. Proposed § 23.1320
would cover the airplanes with the greatest threat of lightning. In addition, the proposed language
clarifies that the failure consequence of interest is at the airplane system level, which allows
credit for design and installation architecture.
vi. Proposed § 23.1325, High-Intensity Radiated Fields (HIRF) Protection
Proposed § 23.1325 would require that electrical and electronic systems that perform a
function whose failure would prevent the continued safe flight and landing of the airplane, be
designed and installed such that the airplane level function is not adversely affected during and
after the time the airplaneis exposed to the HIRF environment. Proposed § 23.1325 would also
require that these systems automatically recover normal operation of that function in a timely
manner after the airplane is exposed to the HIRF environment, unless the system’s recovery
conflicts with other operational or functional requirements of the system. Proposed § 23.1325,
High-Intensity Radiated Fields (HIRF) protection, would incorporate the safety intent of current
§ 23.1308, High-intensity Radiated Fields (HIRF) protection.
Before § 23.1308, amendment 23-57 (72 FR 44016, August 6, 2007), the requirements
for HIRF protection were found in § 23.1309. The adoption of § 23.1308 was justified because
there was an increased use of complex systems and equipment, including engine and flight
controls, in small airplanes. These systems are more susceptible to the adverse effects of
operation in the HIRF environment.
The electromagnetic HIRF environment results from the transmission of electromagnetic
energy from radar, radio, television, and other ground-based, ship-borne, or airborne radio
frequency transmitters. The HIRF environment changes as the number and types of transmitters
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change. During the 1990’s, extensive studies were conducted to define the environment that then
existed. The FAA codified this environment in amendment 23-57 in appendix J to part 23—
HIRF Environments and Equipment HIRF Test Levels.
Proposed § 23.1325 would require the applicant to address the HIRF environment
expected in service instead of solely relying on the HIRF environment codified in appendix J.
The current appendix J to part 23 would become a means of compliance as the accepted expected
HIRF environment, until other levels were accepted by the Administrator. This would allow the
test levels to match the current threat as the environment changes over time. Additionally, the
proposed language would clarify that the failure consequence of interest is at the airplane level,
which allows credit for design and installation architecture.
vii. Proposed § 23.1330, System Power Generation, Storage, and Distribution
Proposed § 23.1330(a) would require that the power generation, storage, and distribution
for any system be designed and installed to supply the power required for operation of connected
loads during all likely operating conditions. Also, proposed § 23.1330(b) would require the
design installation ensure no single failure or malfunction would prevent the system from
supplying the essential loads required for continued safe flight and landing. Proposed § 23.1330
would also require the design and installation have enough capacity to supply essential loads,
should the primary power source fail, for at least 30 minutes for airplanes certificated with a
maximum altitude of 25,000 feet or less, and at least 60 minutes for airplanes certificated with a
maximum altitude over 25,000 feet.
Proposed § 23.1330 would capture the safety intent of the current §§ 23.1310, Power
source capacity and distribution; 23.1351, General; 23.1353, Storage battery design and
installation; and 23.1357, Circuit protective devices. The intent is to ensure airplane power
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generation and the related distribution systems are designed for adequate capacity and safe
operation under anticipated use and in the event of a failure or malfunction.
viii. Proposed § 23.1335, External and Cockpit Lighting
Proposed § 23.1335 would require an applicant to design and install all lights to prevent
adverse effects on the performance of flightcrew duties. Proposed § 23.1335 would require
position and anti-collision lights, if installed, to have the intensities, flash rate, colors, fields of
coverage, and other characteristics to provide sufficient time for another aircraft to avoid a
collision. Proposed § 23.1335 would require position lights, if installed, to include a red light on
the left side of the airplane, a green light on the right side of the airplane, spaced laterally as far
apart as practicable, and a white light facing aft, located on an aft portion of the airplane or on
the wing tips.
Proposed § 23.1335 would require that an applicant design and install any taxi and
landing lights, if required by operational rules, so they provide sufficient light for night
operations. For seaplanes or amphibian airplanes, this section would also require riding lights to
provide a white light visible in clear atmospheric conditions. Airplanes moored or maneuvering
on water are by mairtime law considered watercraft; therefore, riding lights are required for
seaplanes and amphibians during water operations.
To encourage the installation of internal and external lighting systems with new safety
enhancing technology and streamline the certification process, the FAA proposes removing most
of the current prescriptive requirements and the detailed means of compliance for these
requirements from current part 23. The current prescriptive requirements would be replaced with
performance-based requirements. The FAA expects that current means of compliance would
continue to be used for the traditional airplane designs under part 23.
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Required lighting for the operation requested by an applicant would have to be installed
and approved as part of the type design. The current rule requires that interior and exterior
lighting function as intended without causing any safety hazard in normal operation. The
proposed rule would require external lighting to make each airplane visible at night at a distance
allowing each pilot to maneuver in sufficient time to avoid collision. The current rule specifies a
specific amount of light illumination accounting for airframe obstructions. The FAA proposes
removing this specified location and amount of illumination because it is more appropriate as
means of compliance. The FAA does not consider small obstructions caused by airplane
structure to be a safety issue.
This section would capture the safety intent of current §§ 23.1381, Instrument lights,
paragraph (c); 23.1383, Taxi and landing lights, paragraphs (a), (b) and (c); 23.1385, Position
light system installation, paragraphs (a), (b) and (c); 23.1387, Position light dihedral angles;
23.1389, position light distribution and intensities; 23.1391, Minimum intensities in the
horizontal plane of position lights; 23.1393, Minimum intensities in any vertical plane of
position lights; 23.1395, Maximum intensities in overlapping beams of position lights; 23.1397,
color specifications; 23.1399, Riding light; and 23.1401, Anticollision light system, paragraphs
(a), (a)(1), (b), (c), (d), (e), and (f).
ix. Proposed § 23.1400, Safety Equipment
Proposed § 23.1400 would require safety and survival equipment, required by the
operating rules of this chapter, to be reliable, readily accessible, easily identifiable, and clearly
marked to identify its method of operation.
The FAA proposes requirements for safety equipment needed for emergency landings
and ditching when required by operational rules, and removal of the duplicative rules that are
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found in current part 23. Required safety equipment would have to be installed, located, and
accessible for use in an emergency, and secured against emergency landing accelerations. The
proposed rule would require safety, ditching, and survival equipment, be reachable, plainly
marked for operation, and not be damaged in survivable emergency landings.
This section would capture the safety intent of current §§ 23.1411, Safety equipmentGeneral, paragraphs (a) and (b)(1); and 23.1415; Ditching equipment, paragraphs (a), (c), and
(d).
x. Proposed § 23.1405, Flight In Icing Conditions
Proposed § 23.1405 would require an applicant to demonstrate its ice protection system
would provide for safe operation, if certification for flight in icing conditions is requested.
Proposed § 23.1405 would also require these airplanes to be protected from stalling when the
autopilot is operating in a vertical mode. Proposed § 23.1405 would require this demonstration
be conducted in atmospheric icing conditions specified in part 1 of appendix C to part 25 of this
chapter, and any additional icing conditions for which certification is requested.
Proposed § 23.1405 would capture the safety intent of current § 23.775(a) Windshields
and windows, and § 23.1419, Ice protection. Proposed § 23.1405 would also increase safety by
adding icing conditions beyond those specified in the current § 23.1419. The proposed § 23.1405
would only apply to airplanes seeking certification for flight in icing. The current § 23.1419 only
applies to airplanes seeking certification for flight in icing; however, ice protection systems can
be certified without certification for flight in icing.
The current ice protection system requirements in § 23.1419(a) would be captured in
proposed § 23.1405(a)(1). The proposed rule would require an applicant to show systems are
adequate in the icing conditions for which certification is requested. As in the current rule, ice
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protection systems would have to be shown to be adequate in the icing conditions of appendix C
to part 25. Freezing drizzle and freezing rain icing conditions are optional icing conditions in
which the airplane may be certificated to operate. These icing conditions, which the FAA added
to appendix O to part 25 in amendment 25-140, are not being defined in proposed § 23.230. The
FAA determined that the definition of these optional icing conditions is more appropriate as a
means of compliance. Ice crystal conditions are added to this proposal for certain air data probes
to harmonize with EASA requirements.
The Part 23 Icing ARC recommendations on activation and operation of ice protection
systems would be used as a means of compliance to proposed § 23.1405(a)(1). This proposal
would satisfy the intent of NTSB Safety Recommendations A-07-14 and A-07-15.
Proposed § 23.1405(a)(2) is the Part 23 Icing ARC recommendation for airplanes
certified under part 23 in icing and is based on NTSB safety recommendation A-10-12. The
target for this proposed rule is older airplanes adding an autopilot for first time, modifying
certain autopilots on airplanes with a negative service history in icing, or significant changes that
affect performance or flight characteristics. Proposed § 23.1405 would require, under the
changed product rule, to add proposed § 23.1405(a)(2) to the certification basis without requiring
the remainder of § 23.1405 for certain autopilot modifications. For new airplanes, a stall warning
system that complies with proposed § 23.230 would comply with proposed § 23.1405(a)(2). The
vertical mode is a prescriptive requirement to limit the applicability. Simple autopilots such as a
wing leveler would not be affected by this requirement. Numerous icing accidents have shown
that unrecognized airspeed loss can occur with autopilots in altitude hold mode or vertical speed
mode. Demonstration, as a means of compliance, may include design and/or analysis and does
not mean natural icing flight tests are required.
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xi. Proposed § 23.1410, Pressurized System Elements
Proposed § 23.1410 would require the minimum burst pressure of—

Hydraulic systems be at least 2.5 times the design operating pressure with the
proof pressure at least 1.5 times the maximum operating pressure;

Pressurization system elements be at least 2.0 times, and proof pressure be at least
1.5 times, the maximum normal operating pressure; and

Pneumatic system elements be at least 3.0 times, and proof pressure be at least 1.5
times, the maximum normal operating pressure.
Additionally, this proposed section would also require that other pressurized system elements
have pressure margins that take into account system design and operating conditions.
This section would capture the safety intent of current §§ 23.1435, Hydraulic system,
paragraphs (a)(4) and (b); 23.1437, Accessories for multiengine airplanes; and 23.1438,
Pressurization and pneumatic systems, paragraphs (a) and (b).
xii. Proposed § 23.1457, Cockpit Voice Recorders
The FAA is not proposing to revise current § 23.1457 because amendment 23-58
(73 FR 12542, March 7, 2008) and corrected on July 9, 2009 (74 FR 32799), was written to
standardize the cockpit voice recorder rules to address the NTSB's recommendations
(70 FR 9752, February 28, 2005). The FAA agrees with NTSB recommendation numbers A-9689, A-96-171, A-99-18, and parts of A-99-16 and A-99-17 and believes changing the current rule
to remove prescriptive requirements could hinder the conduct of future accident investigations
and be detrimental to aviation accident investigations.
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xiii. Proposed § 23.1459, Flight Data Recorders
The FAA is not making any substantive changes to the current § 23.1459 because
amendment 23-58 (73 FR 12541, March 7, 2008) was written to standardize the flight data
recorder rules to address the NTSB's recommendations. The FAA agrees with NTSB
recommendation numbers A-96-89, A-96-171, A-99-18, and parts of numbers A-99-16 and A99-17 and believes changing the current rule to remove prescriptive requirements could hinder
the conduct of future accident investigations and be detrimental to aviation safety. Proposed
§ 23.1459(a)(1), however, is amended to revise current references to §§ 23.1323, Airspeed
indicating system; 23.1325, Static pressure system; and 23.1327, Magnetic direction indicator, as
those sections are not contained in this NPRM.
xiv. Current Subpart F Regulations Relocated to Other Proposed Subparts
The requirement currently in § 23.1419(a) to comply with subpart B requirements to
show safe operating capability is moved to proposed § 23.230 as recommended by the Part 23
Icing ARC and Part 23 Reorganization ARC.
Ice protection of engine inlets would move to proposed § 23.940, Powerplant ice
protection. The Part 23 Reorganization ARC had proposed that § 23.1405 include these
requirements, as well as heated pitot probe requirements for IFR airplanes. The FAA decided to
separate them since compliance with proposed §§ 23.940 and 23.1300 would be required for all
airplanes, whereas compliance with § 23.1405 would be optional. The FAA wants to avoid
potential confusion on TCDS interpretation as to whether an airplane is certified for flight in
icing.
The requirements currently in § 23.1381, Instrument lights, paragraphs (a) and (b) would
be relocated to proposed § 23.1500, Flightcrew Interface. The requirements currently in
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§ 23.1411, Safety equipment-General, paragraph (b)(2) would be relocated to proposed § 23.600,
Emergency conditions.
xv. Removal of Subpart F of the Current Regulations
When the FAA evaluated the current regulations, it determined that the prescriptive icing
requirements in §§ 23.1323, Airspeed indicating system, and 23.1325, Static pressure system,
would be means of compliance to proposed § 23.1405(a)(1). The current requirement for a
heated pitot probe or an equivalent means on an IFR certified and a flight in icing conditions
airplane in current § 23.1323(d) would become a means of compliance for proposed § 23.1300.
The part 23 re-write ARC had recommended that proposed § 23.1405 include the
requirement for a heated pitot probe on an IFR certified airplane, but the FAA determined this
would be better addressed on a performance standard under proposed § 23.1300, because
proposed § 23.1405 would only apply to icing certified airplanes. High altitude mixed phase and
ice crystal conditions for certain high-performance airplanes, and ice protection requirements for
stall warning and angle of attack would be means of compliance. The proposed standard would
harmonize with EASA requirements.
Current § 23.1416 would be removed since the requirements for proper inflation and
annunciation of operation of pneumatic boots would be covered on a performance basis in
proposed §§ 23.1300 and 23.1305. This would reflect that all types of ice protection systems
have annunciation requirements, and would eliminate unnecessary annunciations. The Part 23
Icing ARC recommended this approach.
The analysis required in the current § 23.1419(a), and all the requirements in the current
§ 23.1419(b) and (c), would become means of compliance to proposed 1405(a) and would be
removed.
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Current § 23.1419(d) requires a means to detect critical ice accretions, including night
lighting. The Part 23 Icing ARC had proposed a new § 23.1403 to replace these ice detection
requirements, which would also address the SLD detection required by proposed § 23.230. These
ice detection requirements are more appropriately addressed as a means of compliance to
accommodate new technology. For example, visual ice accretion detection as a means to activate
ice protection systems is no longer necessary on some designs, examples being primary ice
detection systems and icing conditions detection systems. However, there would remain a
requirement for pilots to detect severe ice accretions, and this would be addressed in proposed
§ 23.230(b).
When the FAA evaluated the current regulations, it determined that the prescriptive
requirements in §§ 23.1323, Airspeed indicating system; 23.1325, Static pressure system;
23.1327, Magnetic direction indicator; 23.1329, Automatic pilot system; 23.1335, Flight director
systems; 23.1337, Powerplant instruments installation; 23.1353, Storage battery design and
installation; and 23.1357, Circuit protective devices, would be covered on a performance basis
by proposed §§ 23.1300; 23.1305; 23.1310; and 23.1315.
Current § 23.1401, Anticollision light system, paragraph (a)(2) would be removed as
introductory material. Current § 23.1415, ditching equipment, paragraph (b) would be removed
but could serve as a means of compliance. The current §§ 23.1435, Hydraulic systems,
paragraphs, (a), (a)(1), (a)(2), (a)(3), and (c); 23.1438, Pressurization and pneumatic systems,
paragraph (c), would be removed as prescriptive design and means of compliance. Current §
23.1443, Minimum mass flow of supplemental oxygen, paragraph (d) would be removed as a
definition. Current § 23.1445, paragraph (e) would be removed as redundant to current § 91.211,
paragraph (a)(3).
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7. Subpart G—Flightcrew Interface and Other Information
a. General Discussion
The FAA proposes to expand subpart G to address not only current operating limitations
and information, but also the concept of flightcrew interface. Based on current technologies, the
FAA anticipates that new airplanes will heavily rely on automation and systems that require new
and novel pilot or flightcrew interface. The FAA is proposing to address the pilot interface issues
found in subparts D and F with proposed § 23.1500. Otherwise, subpart G retains the safety
requirements from the current rules without change. Refer to appendix 1 of this preamble for a
cross-reference table detailing how the current regulations are addressed in the proposed part 23
regulations.
b. Specific Discussion of Changes
i. Proposed § 23.1500, Flightcrew Interface
Proposed § 23.1500 would require the pilot compartment and its equipment to allow the
pilot(s) to perform their duties, including taxi, takeoff, climb, cruise, descent, approach, and
landing; and perform any maneuvers within the operating envelope of the airplane, without
excessive concentration, skill, alertness, or fatigue. Proposed § 23.1500 would also require an
applicant to install flight, navigation, surveillance, and powerplant controls and displays so
qualified flightcrew could monitor and perform all tasks associated with the intended functions
of systems and equipment in order to make the possibility that a flightcrew error could result in a
catastrophic event highly unlikely. Proposed § 23.1500 would capture the safety intent of current
part 23 rules that are directly related to the pilot or flightcrew interface with the airplane.
Interfaces include controls, displays, and visibility requirements.
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Current and anticipated technologies that affect how the pilot interfaces with the airplane
are expected to expand faster than other technologies. The FAA believes that significant safety
improvements can result from the evolution of how the pilot interfaces with the airplane. Pilot
workload is a major factor in causing accidents, but it is almost impossible to connect workloadrelated mistakes to an accident after the accident has happened. Evidence from large airplane
accidents, where we have recorded data as well as research, points to the importance of the pilot
interface and associated mistakes as causal factors in aircraft accidents. The smart use of
automation and phase-of-flight-based displays could reduce pilot workload and increase pilot
awareness.
The converse is also true. Equipment is becoming available faster than manufacturers and
the FAA can evaluate it. Determining the safety risks and recognizing the safety benefits of new
technology available to the pilot is important. For this reason, the proposed language addresses
the safety issues of the current §§ 23.699, Wing flap position indicator; 23.745 Nose/Tail wheel
steering, 23.1303, Flight and navigation instruments, paragraph (g)(3); 23.1321, Arrangement
and visibility, paragraphs (a),(b),(d), and (e); 23.1311, Electronic display instrument systems,
paragraphs (a)(6) and (7); 23.771, Pilot compartment, paragraph (a), 23.773(a) Pilot
compartment view, 23.777, Cockpit controls; 23.779, Motion and effect of cockpit controls; and
23.781, Cockpit control knob shape; are addressed in proposed § 23.1500(a) and (b). The
proposed language would allow the FAA to rapidly evaluate new equipment for concentration,
skill, alertness, and fatigue against pilot workload as is current practice. More importantly, the
FAA would remove the prescriptive requirements from the current rules to allow for alternative
approaches to pilot interface that would reduce pilot workload or increase safety.
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ii. Proposed § 23.1505, Instrument Markings, Control Markings, and Placards
Proposed § 23.1505 would require each airplane to display in a conspicuous manner any
placard and instrument marking necessary for operation. Proposed § 23.1505 would also require
an applicant to clearly mark each cockpit control, other than primary flight controls, as to its
function and method of operation and include instrument marking and placard information in the
AFM. The consolidation of these sections appears large, but many of these sections contain one
prescriptive requirement that, in many cases, is based on traditional airplanes, instruments, and
equipment.
iii. Proposed § 23.1510, Airplane Flight Manual
Proposed § 23.1510 would require an applicant to furnish an AFM with each airplane that
contains the operating limitations and procedures, performance information, loading information,
and any other information necessary for the operation of the airplane.
The proposed rules capture the prescriptive list of information that is considered
necessary for the operation of the traditional airplanes. The current rules contain very
prescriptive and detailed information. Furthermore, that level of detail assumes a traditional
airplane configuration and operation. The FAA proposes to remove this detail from the rule
because it is more appropriate as means of compliance. Currently, the majority of airplanes
certificated under part 23 already use an industry standard to develop their AFMs—General
Aviation Manufactures Association Specification 1, Specification for Pilot’s Operating
Handbook26. The FAA already accepts this industry standard for many airplanes certificated
under part 23 because it includes the information that is currently required in part 23. The FAA
26
See www.regulations.gov (Docket # FAA-2015-1621)
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believes that allowing alternative approaches to information would facilitate new technology
integration into airplanes certified under part 23.
The proposed § 23.1510(d) would capture the safety intent of the current §§ 23.1505,
Airspeed limitations, thru 23.1527, Maximum operating altitude, specific to operating limitations
and other limitations and information necessary for safe operation.
iv. Proposed § 23.1515, Instructions for Continued Airworthiness
Proposed § 23.1515 would require an applicant to prepare Instructions for Continued
Airworthiness in accordance with proposed appendix A to this part, that are acceptable to the
Administrator, prior to the delivery of the first airplane or issuance of a standard certification of
airworthiness, whichever occurs later. This proposed section would capture the current § 23.1529
without change. The FAA proposes renaming Appendix G to Part 23—Instructions for
Continued Airworthiness, to Appendix A to Part 23— Instructions for Continued Airworthiness.
8. Appendices to Part 23
a. General Discussion
Many of the appendices to part 23 contain information that the FAA believes would be
more appropriate as a means of compliance, with the exception of Appendix G to Part 23–
Instructions for Continued Airworthiness. Appendices A, B, C, D, E, F, H, and J would be
removed and appendix G would be renamed Appendix A–Instructions for Continued
Airworthiness.
b. Specific Discussion of changes
i. Proposed Appendix A to Part 23 – Instructions for Continued Airworthiness
The FAA proposes renaming Appendix G to Part 23—Instructions for Continued
Airworthiness, as Appendix A to Part 23— Instructions for Continued Airworthiness.
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ii. Removal of Appendices to Part 23
Appendix A to Part 23—Simplified Design Load Criteria. The FAA proposes to remove
this appendix because the content is more appropriate for inclusion in methods of compliance.
Appendix B to Part 23—[Reserved]. The FAA proposes to remove this appendix because
it has been reserved since amendment 23-42. There is no reason to include this appendix in the
proposed revision to part 23.
Appendix C to Part 23—Basic Landing Conditions. The FAA proposes to remove this
appendix because the content is more appropriate for inclusion in methods of compliance.
Appendix D to Part 23—Wheel Spin-Up and Spring-Back Loads. The FAA proposes to
remove this appendix because the content is more appropriate for inclusion in methods of
compliance.
Appendix E to Part 23—[Reserved]. The FAA proposes to remove this appendix because
the current appendix is reserved and contains no information.
Appendix F to Part 23—Test Procedure. The FAA proposes to remove this appendix
because this is purely a means of showing compliance for materials that must comply with selfextinguishing flammability requirements.
Appendix H to Part 23—Installation of an Automatic Power Reserve (APR) System. The
FAA proposes to remove this appendix because the FAA believes that the detailed and
prescriptive language of appendix H is more appropriate as means of compliance.
Appendix I to Part 23—Seaplane Loads. The FAA proposes to remove this appendix
because the content is more appropriate for inclusion in methods of compliance.
Appendix J to Part 23—HIRF Environments and Equipment HIRF Test Levels. The
accepted HIRF environment is codified as appendix J to part 23—HIRF Environments and
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Equipment HIRF Test Levels. The proposed language in § 23.1325 would revise this to the
expected HIRF environment. The current appendix J to part 23 would remain an accepted
expected HIRF environment until the Administrator accepted other levels. Any new expected
HIRF environment would be found in FAA guidance material or other standards accepted by the
Administrator. This would allow the certification requirement to match the current threat agreed
to over time. Additionally, the proposed language would clarify that the failure consequence of
interest is at the airplane level, which allows credit for design and installation architecture.
B. Miscellaneous Amendments (§§ 21.9, 21.17, 21.24, 21.35, 21.50, 21.101, 35.1, 35.37, 91.205,
91.313, 91.323, 91.531, 121.310, 135.169, and Appendix E to Part 43)
1. Production of Replacement and Modification Articles (§ 21.9)
The FAA proposes amending § 21.9 by adding paragraph (a)(7) to provide applicants
with an alternative method to obtain FAA approval to produce replacement and modification
articles that are reasonably likely to be installed on type certificated aircraft. We also propose to
revise paragraphs (b) and (c) to specify these articles would be suitable for use in a type
certificated product. These proposed changes would allow an applicant to submit production
information for a specific article, but would not require the producer of the article to apply for
approval of the article’s design or obtain approval of its quality system. Accordingly, approval to
produce a modification or replacement article under proposed § 21.9(a)(7) would not constitute a
production approval as defined in § 21.1(b)(6). The FAA intends to limit use of this procedure to
articles whose improper operation or failure would not cause a hazard. Approval would be
granted to the applicant on a case-by-case basis, specific to the installation proposed, accounting
for potential risk and considering the safety continuum.
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2. Designation of Applicable Regulations (§ 21.17)
The FAA proposes amending § 21.17, by removing the reference to § 23.2, because this
section would be deleted. The requirements in § 23.2 are currently addressed in the operational
rules. Since § 23.2 is a retroactive rule, it is appropriate for the requirement to be in the operating
rules. As a result, the FAA also proposes amending § 91.205 by revising paragraphs (b)(13) and
(b)(14) to ensure removing this requirement would not have any effect on the existing fleet.
3. Issuance of Type Certificate: Primary Category Aircraft (§ 21.24)
The FAA proposes amending § 21.24 by revising paragraph (a)(1)(i) to modify the phrase
as defined by § 23.49 to include reference to amendment 23-62 (76 FR 75736, December
2,2011), effective on January 31, 2012. This revision is necessary to maintain a complete
definition of stall speed in this section, as the current § 23.49 would be removed from the
proposed rule.
4. Flight Tests (§ 21.35)
The FAA proposes amending § 21.35 by revising paragraph (b)(2) to delete the reference
to reciprocating engines and expanding the exempted airplanes to include all low-speed part 23
airplanes 6,000 pounds or less. This proposed change would align the requirements for function
and reliability testing with the proposed changes in part 23 that do not distinguish between
propulsion types. This change would allow the FAA flexibility to address new propulsion types
based on the changes to part 23.
5. Instructions for Continued Airworthiness and Manufacturer's Maintenance Manuals
Having Airworthiness Limitations Sections. (§ 21.50)
The FAA proposes amending § 21.50(b) to reference § 23.1515 rather than § 23.1529.
This change is editorial and would align with the proposed part 23 numbering convention.
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6. Designation of Applicable Regulations (§ 21.101)
The FAA proposes amending § 21.101 by removing the reference to § 23.2 as this section
is proposed to be deleted and is addressed in the operating rules, and to refer to the proposed part
23 certification levels in paragraph (c). The current 6,000-pound reference would be augmented
by the inclusion of simple airplanes, certification level 1 low-speed airplanes, and certification
level 2 low-speed airplanes, in order to align the current rules with the proposed part 23
certification levels.
Additionally, the FAA recognizes that it may be impractical for airplanes certified under
part 23, amendment 23-62, or prior amendments, to move up to the latest amendment for
modifications. Section 21.101 would not be revised to address this circumstance, as this section
allows for certification at a lower amendment level if meeting the current amendment is
impractical. This current provision would allow for compliance to the certification requirements
at amendment 23-62 or earlier when compliance to the latest amendment of part 23 was
determined by the FAA to be impractical.
7. Applicability (§ 35.1)
The FAA proposes amending § 35.1 by replacing the reference to § 23.907 with proposed
§ 23.905(c).
8. Fatigue Limits and Evaluation (§ 35.37)
The FAA proposes amending § 35.37 by replacing the reference to § 23.907 with
proposed § 23.905(c).
9. Altimeter System Test and Inspection (Appendix E to Part 43)
The FAA proposes amending appendix E to part 43 by revising paragraph (a)(2) to
conform with proposed part 23 changes. This proposed change would affect owners and
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operators of part 23 certificated airplanes in controlled airspace under instrument flight rules who
must comply with § 91.411. Concurrent with this rule change, AC 43-6, Altitude Reporting
Equipment and Transponder System Maintenance and Inspection Practices, would be revised to
include a static pressure system proof test acceptable to the Administrator. Additionally, while
reviewing appendix E to part 43, paragraph (a)(2), we noted that it remains silent on parts 27 and
29 rotorcraft and Civil Air Regulations certificated aircraft. The static pressure system proof test
in AC 43-6 ensures the accuracy needed to meet § 91.411 requirements.
10. Powered Civil Aircraft with Standard Category U.S. Airworthiness Certificates:
Instrument and Equipment Requirements (§ 91.205)
The FAA proposes amending § 91.205 by revising paragraphs (b)(13) and (b)(14) to
include the potential for allowing other approved restraint systems. Additionally, paragraph
(b)(14) refers to § 23.561(b)(2), which would be retitled in the proposed revision for structural
strength limits and would be addressed in the means of compliance. Section 91.205(b)(16) would
be deleted and incorporated into (b)(14) with no additional requirements. The part 23 proposal
would delete references to utility and acrobatic categories, as they would be incorporated into the
normal categories that would be redefined into performance-based standards.
11. Restricted Category Civil Aircraft: Operating Limitations (§ 91.313)
The FAA proposes amending § 91.313(g) to include the potential for allowing other
approved restraint systems. Additionally, paragraph (g) includes a regulatory reference to
§ 23.561(b)(2), which would be retitled in the proposed revision as § 23.600, which would be
accompanied by accepted means of compliance. Approval for a shoulder harness or restraint
system, therefore, would require withstanding the static inertia loads specified in § 23.600 during
emergency conditions.
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12. Increased Maximum Certification Weights for Certain Airplanes Operated in Alaska
(§ 91.323)
The FAA proposes amending § 91.323 by removing reference to § 23.337 because this
section would be revised and consolidated with other structural requirements. The relevant
prescriptive requirement(s) maneuvering load factors found in § 23.337 would be added to the
regulation in § 91.323(b)(3).
13. Second In Command Requirements (§ 91.531)
The FAA proposes amending § 91.531(1) and (3) to incorporate the new risk and
performance levels proposed in this NPRM. The FAA proposes deleting the reference to utility,
acrobatic, and commuter categories in part 23. Other divisions would be used to define levels of
certification for normal category airplanes. This proposed amendment would ensure airplanes
certificated in the commuter category in the past and airplanes certificated in the future under the
proposed part 23 airworthiness and performance levels would be addressed in this rule.
14. Additional Emergency Equipment (§ 121.310)
The FAA proposes amending § 121.310(b)(2)(iii) to reflect the reference to § 23.811(b),
effective June 16, 1994. This would be an update to the reference for conformity only. This
amendment would make no change to the requirements of the rule.
15. Additional Airworthiness Requirements (§ 135.169)
The FAA proposes amending § 135.169(b) by deleting the terms, “reciprocating-engine
or turbopropeller-powered”. The current rule limits operation under this part to reciprocatingengine or turbopropeller-powered small airplanes. By amending the paragraph as proposed, other
small airplanes, regardless of propulsion type and including turbojet-powered, would potentially
be considered for certification under this part.
164
The FAA also proposes to allow a small airplane in normal category, in § 135.169(b)(8),
to operate within the rules governing commuter and on demand operations. This action would be
necessary as a result of the proposed part 23 rules which would sunset the commuter category for
newly type certificated airplanes and create a normal category, certification level 4 airplane as
equivalent to the commuter category by applying to 10-19 passengers. This proposed amendment
would allow for the consideration of the new category airplane and to ensure a continued higher
level of safety for commercial operations. Because of the ground-breaking nature of the part 23
proposals, the associated adjustment to performance-based airworthiness standards in future
airplane designs and manufacturing, and the myriad of potential possibilities for attaining a
means of compliance for airplane type certification, the FAA proposes to require the new normal
category certification level 4 airplanes to meet the current airworthiness and performance
standards of the commuter category found in part 23 thru amendment 23-62. These standards are
envisioned to remain as requirements for the new normal category certification level 4 airplanes
into the near-term future, but not the long-term. It is intended that once the new part 23
requirements have proven successful with the new normal category certification levels 1, 2, and
3 airplanes, the FAA would reconsider normal category certification level 4 airplanes for part
135 commercial operations.
VII. Regulatory Notices and Analyses
A. Regulatory Evaluation Summary
Changes to Federal regulations must undergo several economic analyses. First, Executive
Order 12866 and Executive Order 13563 direct that each Federal agency shall propose or adopt a
regulation only upon a reasoned determination that the benefits of the intended regulation justify
its costs. Second, the Regulatory Flexibility Act of 1980 (Public Law 96-354) requires agencies
165
to analyze the economic impact of regulatory changes on small entities. Third, the Trade
Agreements Act (Public Law 96-39) prohibits agencies from setting standards that create
unnecessary obstacles to the foreign commerce of the United States. In developing U.S.
standards, this Trade Act requires agencies to consider international standards and, where
appropriate, that they be the basis of U.S. standards. Fourth, the Unfunded Mandates Reform Act
of 1995 (Public Law 104-4) requires agencies to prepare a written assessment of the costs,
benefits, and other effects of proposed or final rules that include a Federal mandate likely to
result in the expenditure by State, local, or tribal governments, in the aggregate, or by the private
sector, of $100 million or more annually (adjusted for inflation with base year of 1995). This
portion of the preamble summarizes the FAA’s analysis of the economic impacts of this
proposed rule. We suggest readers seeking greater detail read the full regulatory evaluation, a
copy of which we have placed in the docket for this rulemaking.
In conducting these analyses, FAA has determined that this proposed rule: (1) would
have benefits that justify its costs, (2) would not be an an economically “significant regulatory
action” as defined in section 3(f) of Executive Order 12866, (3) would be “significant” as
defined in DOT's Regulatory Policies and Procedures; (4) would have a significant positive
economic impact on small entities; (5) would not create unnecessary obstacles to the foreign
commerce of the United States; and (6) would not impose an unfunded mandate on state, local,
or tribal governments, or on the private sector by exceeding the threshold identified above. These
analyses are summarized below.
1. Total Benefits and Costs of this Rule
The following table shows the estimated benefits and costs of the proposed rule. The
major factors driving the expected costs of this proposal are the additional training tasks,
166
database development, and documentation to FAA and industry part 23 certification engineers.
Benefits consist of safety benefits from preventing stall and spin accidents and savings from
reducing the number of special conditions, exemptions, and equivalent levels of safety. If the
proposed rule saves only one human life by improving stall characteristics and stall warnings,
that alone would result in benefits outweighing the costs.
Estimated Benefits and Costs from 2017 to 2036 (2014 $ Millions)
Costs Safety Benefits + Cost Savings = Total Benefits
Total
$3.9
$19.6 + $12.6 = $32.2
Present value
$3.9
$6.2 + $5.8 = $12.0
2. Who is Potentially Affected by this Rule?
The proposal would affect U.S. manufacturers and operators of new part 23 type
certificated airplanes.
3. Assumptions:
The benefit and cost analysis for the regulatory evaluation is based on the following
factors/assumptions:

The analysis is conducted in constant dollars with 2014 as the base year.

The final rule would be effective in 2017.

The primary analysis period for costs and benefits extends for 20 years, from
2017 through 2036. This period was selected because annual costs and benefits
will have reached a steady state by 2036.

Future part 23 type certifications and deliveries are estimated from historical part
23 type certifications and deliveries.

Costs for the new part 23 type certifications forecasted in the “Fleet Discussion”
section of the regulatory evaluation would occur in year 1 of the analysis interval.
167

Airplane deliveries from the forecasted part 23 type certificates would start in
year 5 of the analysis interval.

The FAA uses a seven percent discount rate for the benefits and costs as
prescribed by OMB in Circular A-4.

The baseline for estimating the costs and benefits of the proposed rule would be
part 23, through amendment 62.

The FAA estimates 335 FAA part 23 certification engineers would require
additional training as a result of this proposal. The FAA assumes that the same
number of industry part 23 certification engineers would also require additional
training as a result of this proposal.

The FAA estimates that this proposal would add 16 hours of training to FAA and
industry part 23 certification engineers.

Since this training program would be on-line, we estimate no travel costs for the
engineers.

FAA pay-band tables and the Bureau of Labor Statistics (BLS) determine the
hourly wages used to estimate the costs to the FAA and applicants.

Using the U.S. Department of Transportation guidance, the wage multiplier for
employee benefits is 1.17.27
4. Benefits of this Rule
The major safety benefit of this proposed rule is to add stall characteristics and stall
warnings that would result in airplane designs that are more resistant to depart controlled flight
27
On January 30, 2014, the DOT published a memo on “Estimating Total Costs of Compensation Based on Wage
Rates or Salaries.” The memo directs the FAA that when a rule requires incremental hours per existing employee,
the wage/salary multiplier is of smaller magnitude because not all categories of employer provided benefits increase
with additional hours worked by an individual employee.
168
inadvertently. The largest number of accidents for small airplanes is a stall or departure-based
LOC in flight. This proposal would also have cost savings by streamlining the certification
process and encouraging new and innovative technology. Streamlining the certification process
would reduce the issuance of special conditions, exemptions, and equivalent level of safety
findings.
5. Costs of this Rule
The proposed rules major costs are the engineer training costs and the certification
database creation costs. Additional costs would also accrue from the proposed controllability and
stall sections that would increase scope over current requirements and manual upgrade costs.
In the following table, we summarize the total estimated compliance costs by category.
The FAA notes that since we assumed that all costs occurred in Year 1 of the analysis interval,
the 2014-dollar costs equal the present value costs.
Total Cost Summary by Category
Type of Cost
§23.200 Controllability
§23.215 Stall characteristics, stall warning, and spins
Engineer Training Costs
Certification Database Costs
Manual Upgrade Costs
Total Costs
Total Costs
(2014$) and P.V.
$276,939
$500,000
$1,149,418
$1,293,750
$700,000
$3,920,106
*These numbers are subject to rounding error.
B. Initial Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (Public Law 96-354) (RFA) establishes “as a
principle of regulatory issuance that agencies shall endeavor, consistent with the objectives of the
rule and of applicable statutes, to fit regulatory and informational requirements to the scale of the
businesses, organizations, and governmental jurisdictions subject to regulation. To achieve this
169
principle, agencies are required to solicit and consider flexible regulatory proposals and to
explain the rationale for their actions to assure that such proposals are given serious
consideration.” The RFA covers a wide-range of small entities, including small businesses, notfor-profit organizations, and small governmental jurisdictions.
Agencies must perform a review to determine whether a rule will have a significant
economic impact on a substantial number of small entities. If the agency determines that it will,
the agency must prepare a regulatory flexibility analysis as described in the RFA.
The FAA believes that this proposed rule could have a significant economic impact on a
substantial number of entities because we believe that this rule could enable the creation of new
part 23 type certificates and new manufacturers. The FAA has been working with U.S. and
foreign small aircraft manufacturers since 2007 to review the life cycle of part 23 airplanes and
determine what needed improvement.
The purpose of this analysis is to provide the reasoning underlying the FAA
determination.
Under Section 603(b) of the RFA, the initial analysis must address:

Description of reasons the agency is considering the action;

Statement of the legal basis and objectives for the proposed rule;

Description of the record keeping and other compliance requirements of
the proposed rule;

All federal rules that may duplicate, overlap, or conflict with the proposed
rule;

Description and an estimated number of small entities to which the
proposed rule will apply; and
170

Describe alternatives considered.
1. Reasons Why the Rule Is Being Proposed
The FAA proposes this action to amend the airworthiness standards for new part 23 type
certificated airplanes to reflect the current needs of the small airplane industry, accommodate
future trends, address emerging technologies, and enable the creation of new part 23
manufacturers and new type certificated airplanes. The proposed changes to part 23 are
necessary to eliminate the current workload of exemptions, special conditions, and equivalent
levels of safety findings necessary to certificate new part 23 airplanes. These proposed part 23
changes would also promote safety by enacting new regulations for controllability and stall
standards and promote new technologies in part 23 airplanes.
2. Statement of the Legal Basis and Objectives
The FAMRA required the Administrator, in consultation with the aviation industry, to
assess the aircraft certification and approval process. In addition, the SARA
directs the FAA to create performance-based regulations for small airplanes and provide for the
use of industry developed consensus standards to allow flexibility in the certification of new
technology.
Accordingly, this proposed rule would amend Title 14 of the Code of Federal Regulations
to revise the airworthiness standards for small airplanes by removing current prescriptive design
requirements and replacing those requirements with risk and performance-based airworthiness
standards.
The FAA’s authority to issue rules on aviation safety is found in Title 49 of the United
States Code. Subtitle I, Section 106 describes the authority of the FAA Administrator. Subtitle
VII, Aviation Programs, describes in more detail the scope of the agency’s authority. This
171
rulemaking is promulgated under the authority described in Subtitle VII, Part A, Subpart III,
Section 44701. Under that section, the FAA is charged with promoting safe flight of civil
airplanes in air commerce by prescribing minimum standards required in the interest of safety for
the design and performance of airplanes. This regulation is within the scope of that authority
because it prescribes new performance-based safety standards for the design of normal category
airplanes.
3. Projected Reporting, Record Keeping and Other Requirements
The FAA expects no more than minimal new reporting and record-keeping compliant
requirements would result from this proposed rule because the prescriptive nature of part 23
would be in other FAA approved documents where future technology can readily be adopted into
the regulatory framework. The FAA requests comment regarding the anticpated reduction in
paperwork and record-keeping burdens that may result from this revision.
4. Overlapping, Duplicative, or Conflicting Federal Rules
The proposed rule would not overlap, duplicate, or conflict with existing federal rules.
5. Estimated Number of Small Firms Potentially Impacted
Under the RFA, the FAA must determine whether a proposed or final rule significantly
affects a substantial number of small entities. This determination is typically based on small
entity size and cost thresholds that vary depending on the affected industry. Using the size
standards from the Small Business Administration for Air Transportation and Aircraft
Manufacturing, we defined companies as small entities if they have fewer than 1,500
employees.28
28
13 CFR Part 121.201, Size Standards Used to Define Small Business Concerns, Sector 48-49 Transportation,
Subsector 481 Air Transportation.
172
There are seven U. S. owned aircraft manufacturers who delivered part 23 airplanes in the
1998-2013 analysis interval. These manufacturers are Adam, American Champion, Cessna,
Hawker Beechcraft, Maule, Quest, and Sino-Swearingen.
Using information provided by the Internet filings and news reports, manufacturers that
are subsidiary businesses of larger businesses, manufacturers that are foreign owned, and
businesses with more than 1,500 employees were eliminated from the list of small entities.
Cessna and Hawker Beechcraft are businesses with more than 1,500 employees. For the
remaining businesses, we obtained company revenue and employment from the above sources.
The base year for the final rule is 2014. Although the FAA forecasts traffic and air carrier
fleets, we cannot determine either the number of new entrants or who will be in the part 23
airplane manufacturing business in the future. Therefore, we use current U.S. part 23 airplane
manufacturers’ revenue and employment in order to determine the number of small entities this
proposed rule would affect.
The methodology discussed above resulted in the following list of five U.S. part 23
airplane manufacturers, with less than 1,500 employees.
Manufacturer
Part 23 Manufacturer 1
Part 23 Manufacturer 2
Part 23 Manufacturer 3
Part 23 Manufacturer 4
Part 23 Manufacturer 5
Number of
Employees
2
65
75
175
2
Annual
Revenue
$110,000
$7,000,000
$35,000,000
$34,000,000
$97,000
From this list of small entity U.S. airplane manufacturers, there are three manufacturers
currently producing part 23 reciprocating engine airplanes; only one manufacturer producing
turboprops and only one producing turbojets. The single manufacturer producing a part 23
turbojet has not delivered an airplane since 2009 and is still working on acquiring the means to
173
start up itsproduction line again. One of the manufacturers producing a part 23 reciprocating
engine airplane has not delivered an airplane since 2007 and is working on acquiring the means
to start up their production line again. The FAA is not aware that either of these manufacturers is
considering a new airplane for part 23 type certification in the future and therefore this proposed
rulemaking would most likely not add costs to these two manufacturers because the proposed
rule only affects new part 23 type certificates.
For the remaining two reciprocating engine part 23 airplane manufacturers, their last type
certificates were issued in 1961 and 1970. The 1961 type certificate was issued for the only
airplane this manufacturer produces and the manufacturer with the 1970 type certificate produces
one other airplane that was type certificated in 1941. The last small entity manufacturer produces
only turboprop airplanes and it started delivering airplanes in 2007. Again, the FAA is not aware
that any of these manufacturers is considering a new airplane for part 23 type certification in the
future and therefore this proposed rulemaking would most likely not add costs for it.
While this rulemaking may enable the creation of new manufacturers, the FAA is not
aware of any new small entity part 23 manufacturers who want a type certification in the future
for a new part 23 airplane. However, by simplifying and lowering the costs for certification of
new small airplanes, barriers to entry may be lowered and thus new manufacturers may emerge.
6. Cost and Affordability for Small Entities
In 2009, a joint FAA/industry team finalized the Part 23 CPS. This proposed rulemaking
resulted from this study by the recommendation to use consensus standards to supplement the
regulatory language. Since then, the FAA and the part 23 industry have worked together to
develop common part 23 airplane certification requirements for this rulemaking. In 2011, with
the Part 23 CPS as a foundation, the FAA formed the Part 23 Reorganization ARC. The ARC
174
consisted of large and small entity domestic and international businesses. We contacted the part
23 airplane manufacturers, the ARC, and GAMA for specific cost estimates for each section
change for the rule and they all believe that this proposed rule would have a minimal cost impact
on their operations and in many cases, would have significant cost savings by streamlining the
part 23 type certification process. Many of the ARC members collaborated and provided a joint
cost estimate for the proposed rule.
The ARC has informed us that the proposed rule would a save the manufacturers design
time for the certification of part 23 airplanes by reducing the number of exemptions, equivalent
level of safety findings and special conditions required to incorporate new and future technology
into their new airplane certifications. The proposed rule would also require manuals to be
updated and database development. We expect these updates to be minimal and request commen
on these anticipated costs and overall reduction in paperwork burden.
The ARC has also informed us that every other section of this proposed rule would be
cost-neutral since the majority of the prescriptive requirements in part 23 would be moved from
part 23. The FAA expects that these current requirements would form the basis for consensus
standards that would be used as a means of compliance to the proposed performance based
regulations.
The FAA expects this proposed rule could have a positive economic impact to small
entities because it would enable new businesses to produce new part 23 type certificated
airplanes while maintaining a safe operating environment in the NAS. This proposal is based on
the ARC’s recommendations and would allow for the use of consensus standards that have been
developed in partnership with industry. Therefore, the FAA believes that this proposed rule
could have a positive significant economic impact on a substantial number of entities.
175
7. Alternative Analysis
a. Alternative 1
The FAA would continue to issue special conditions, exemptions, and equivalent level of
safety findings to certificate part 23 airplanes. As this approach would not follow congressional
direction, we choose not to continue with the status quo.
b. Alternative 2
The FAA would continue to enforce the current regulations that affect stall and
controllability. The FAA rejected this alternative because the accident rate for part 23 airplanes
identified a safety issue that had to be addressed.
c. Alternative 3
The FAA notes that a multi-engine part 23 aircraft manufacturer could decide it wants to
comply with § 23.200(b) by making the airplane capable of climbing after a critical loss by
installing larger engines. But this is a very expensive alternative that would raise certification
costs and operating costs and we believe that part 23 aircraft manufacturers would not make the
airplane capable of climbing after a critical loss by installing larger engines.
The FAA solicits comments regarding this determination.
C. International Trade Impact Assessment
The Trade Agreements Act of 1979 (Public Law 96-39), as amended by the Uruguay
Round Agreements Act (Public Law 103-465), prohibits Federal agencies from establishing
standards or engaging in related activities that create unnecessary obstacles to the foreign
commerce of the United States. Pursuant to these Acts, the establishment of standards is not
considered an unnecessary obstacle to the foreign commerce of the United States, so long as the
standard has a legitimate domestic objective, such as the protection of safety, and does not
176
operate in a manner that excludes imports that meet this objective. The statute also requires
consideration of international standards and, where appropriate, that they be the basis for U.S.
standards. The FAA has assessed the potential effect of this proposed rule and determined that
the standards are necessary for aviation safety and would not create unnecessary obstacles to the
foreign commerce of the United States.
D. Unfunded Mandates Assessment
Title II of the Unfunded Mandates Reform Act of 1995 (Public Law 104-4) requires each
Federal agency to prepare a written statement assessing the effects of any Federal mandate in a
proposed or final agency rule that may result in an expenditure of $100 million or more (in 1995
dollars) in any one year by State, local, and tribal governments, in the aggregate, or by the
private sector; such a mandate is deemed to be a "significant regulatory action." The FAA
currently uses an inflation-adjusted value of $155.0 million in lieu of $100 million. This
proposed rule does not contain such a mandate; therefore, the requirements of Title II of the Act
do not apply.
E. Paperwork Reduction Act
The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires that the FAA
consider the impact of paperwork and other information collection burdens imposed on the
public. The information requirements for aircraft certification are covered by existing OMB No.
2120-0018. Burdens associated with special conditions, ELOS, and exemptions are not
quantified in this collection because the need to seek relief under one of these options is
dependent on each applicant and is difficult to quantify. It is expected that this rulemaking would
reduce the number of special conditions, ELOS, and exemptions filed, thus reducing paperwork
and processing time for both the FAA and industry. It would also maintain the fundamental
177
safety requirements from the current part 23 regulations but allow more flexibility in airplane
designs, faster adoption of safety enhancing technology, and reduce the regulatory cost burden.
To estimate savings driven by this change, the FAA counted the special conditions, ELOS, and
exemption applications submitted to the FAA for part 23 aircraft between 2012 and 2013 and
divided the number by two years for an average of 47 applications per year.29 The ARC report
offered a similar average of 37 applications per year.30 Additionally, the FAA counted the
number of pages per application for all 47 applications to obtain an average number of pages per
application. For special conditions, there were approximately 21 pages, 16 pages for an
exemption, and 15 pages per ELOS application. The FAA assumes that the applicant and each
FAA office that reviews the application spend 8 hours on research, coordination, and review per
page. The ARC also noted “an ELOS finding or exemption can take the FAA between 4 to12
months to develop and approve. The applicant spends roughly the same amount of time as the
FAA in proposing what they need and responding to FAA questions for SC, exemption, or
ELOS.”31
The number of applications is multiplied by the number of pages and by the hourly wage
for the applicant and different FAA offices to account for the cost to the FAA and the applicant.
The estimated hourly wage is $74.10 for a Small Airplane Directorate employee32, $50.75 for an
Aircraft Certificate Office employee33, and $60.58 for an engineer34 employed by the applicant.
29
https://my.faa.gov/org/linebusiness/avs/offices/air/tools/cert.html
A report from the 14 CFR Part 23 Reorganization Aviation Rulemaking Committee to the Federal Aviation
Administration; Recommendation for increasing the safety of small general aviation airplanes certificated to 14 CFR
part 23, June 5, 2013, Table 7.1 – Special Conditions, Exemptions, Equivalent Safety Findings, Page 55
31
Ibid., 54.
32
2014 FAA Bay Band, Average K Band Salary (Rest of the U.S.) plus wage multiplier for benefits
https://employees.faa.gov/org/staffoffices/ahr/program_policies/policy_guidance/hr_policies/hrpm/comp/comp_ref/
2014payadjustment/
33
2014 FAA Bay Band, Average I Band Salary (Rest of the U.S.) plus wage multiplier for benefits
https://employees.faa.gov/org/staffoffices/ahr/program_policies/policy_guidance/hr_policies/hrpm/comp/comp_ref/
2014payadjustment/
30
178
Annual cost equals the sum of the associated costs of special conditions, exemptions, plus
equivalent level of safety. Yearly cost totals roughly $502,469 for the Small Airplane
Directorate, $344,172 for Aircraft Certificate Offices, and $410,823 for the applicants. Tables 7,
8, and 9 show cost by office and applicant as well as by special condition, exemption, and ELOS.
34
National Occupational Employment and Wage Estimates United States, May 2014; Aerospace Engineer mean
hourly wage, NAIC code 17-2011 plus wage multiplier for benefits http://www.bls.gov/oes/current/oes_nat.htm#170000 A more detailed discussion is provided in the “Costs” section below.
179
Table 7. Savings from Special Conditions (SC)*
FAA SAD
ManSavings
hours
FAA ACO
ManSavings
hours
Applicant
ManSavings
hours
Part 23
Section
Avg. Number
of SC
(2012-2013 )
Avg.
Number of
Pages
143
171
173
175
177
251
361
562
572
573
574
613
627
629
901
939
951
961
973
977
1141
1301
1305
1308
1309
1329
1337
1521
1557
0.5
0.5
0.5
0.5
0.5
0.5
1
1
0.5
0.5
0.5
0.5
0.5
1.5
1
0.5
1
1
1
1.5
0.5
0.5
1
0.5
1
0.5
0.5
1
1
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
20.8
83
83
83
83
83
83
166
166
83
83
83
83
83
250
166
83
166
166
166
250
83
83
166
83
166
83
83
166
166
$6,165
$6,165
$6,165
$6,165
$6,165
$6,165
$12,330
$12,330
$6,165
$6,165
$6,165
$6,165
$6,165
$18,495
$12,330
$6,165
$12,330
$12,330
$12,330
$18,495
$6,165
$6,165
$12,330
$6,165
$12,330
$6,165
$6,165
$12,330
$12,330
83
83
83
83
83
83
166
166
83
83
83
83
83
250
166
83
166
166
166
250
83
83
166
83
166
83
83
166
166
$4,223
$4,223
$4,223
$4,223
$4,223
$4,223
$8,445
$8,445
$4,223
$4,223
$4,223
$4,223
$4,223
$12,668
$8,445
$4,223
$8,445
$8,445
$8,445
$12,668
$4,223
$4,223
$8,445
$4,223
$8,445
$4,223
$4,223
$8,445
$8,445
83
83
83
83
83
83
166
166
83
83
83
83
83
250
166
83
166
166
166
250
83
83
166
83
166
83
83
166
166
$5,040
$5,040
$5,040
$5,040
$5,040
$5,040
$10,081
$10,081
$5,040
$5,040
$5,040
$5,040
$5,040
$15,121
$10,081
$5,040
$10,081
$10,081
$10,081
$15,121
$5,040
$5,040
$10,081
$5,040
$10,081
$5,040
$5,040
$10,081
$10,081
0.5
20.8
83
$6,165
83
$4,223
83
$5,040
0.5
20.8
83
$6,165
83
$4,223
83
$5,040
0.5
0.5
20.8
20.8
83
83
$6,165
$6,165
83
83
$4,223
$4,223
83
83
$5,040
$5,040
0.5
20.8
83
$6,165
83
$4,223
83
$5,040
0.5
24.5
20.8
728
83
4077
$6,165
$302,080
83
4077
$4,223
$206,914
83
4077
$5,040
$246,983
3Pt Restraint with
Airbag
Inflatable Restraint
Electronic Engine
Controls
Fuel Jettisoning
Load Alleviation
System
Side Facing Seat
with Airbag
Totals
*These numbers are subject to rounding error.
180
Table 8. Savings from Exemptions*
Part 23
Section
Avg. Number
Exemptions
(2012-2013 )
Avg. Number
of Pages
Man-hours
Savings
Man-hours
Savings
Man-hours
Savings
1359
1549
177
49
562
1419
Totals
0.5
0.5
0.5
1
1
0.5
4
15.6
15.6
15.6
15.6
15.6
15.6
94
62.4
62.4
62.4
124.8
124.8
62.4
499
$4,624
$4,624
$4,624
$9,247
$9,247
$4,624
$36,989
62
62
62
125
125
62
499
$3,167
$3,167
$3,167
$6,334
$6,334
$3,167
$25,336
62
62
62
125
125
62
499
$3,780
$3,780
$3,780
$7,561
$7,561
$3,780
$30,243
FAA SAD
FAA ACO
Applicant
*These numbers are subject to rounding error.
Table 9. Savings from Equivalent Level of Safety (ELOS)*
Part 23
Section
Avg. Number
ELOS
(2012-2013 )
Avg. Number
of Pages
Man-hours
Savings
Man-hours
Savings
Man-hours
Savings
145
207
672
777
779
781
807
815
841
973
1092
1145
1305
1311
1353
1357
1397
1401
1419
1443
1505
1545
1549
Totals
1
1
0.5
1.5
0.5
1.5
0.5
0.5
1
0.5
0.5
1
1.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
2.5
19
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
14.9
343
119.2
119.2
59.6
178.8
59.6
178.8
59.6
59.6
119.2
59.6
59.6
119.2
178.8
59.6
59.6
59.6
59.6
59.6
59.6
59.6
59.6
59.6
298
2205
$8,832
$8,832
$4,416
$13,249
$4,416
$13,249
$4,416
$4,416
$8,832
$4,416
$4,416
$8,832
$13,249
$4,416
$4,416
$4,416
$4,416
$4,416
$4,416
$4,416
$4,416
$4,416
$22,081
$163,400
119
119
60
179
60
179
60
60
119
60
60
119
179
60
60
60
60
60
60
60
60
60
298
2205
$6,050
$6,050
$3,025
$9,075
$3,025
$9,075
$3,025
$3,025
$6,050
$3,025
$3,025
$6,050
$9,075
$3,025
$3,025
$3,025
$3,025
$3,025
$3,025
$3,025
$3,025
$3,025
$15,125
$111,923
119
119
60
179
60
179
60
60
119
60
60
119
179
60
60
60
60
60
60
60
60
60
298
2205
$7,221
$7,221
$3,611
$10,832
$3,611
$10,832
$3,611
$3,611
$7,221
$3,611
$3,611
$7,221
$10,832
$3,611
$3,611
$3,611
$3,611
$3,611
$3,611
$3,611
$3,611
$3,611
$18,054
$133,597
FAA SAD
FAA ACO
Applicant
*These numbers are subject to rounding error.
Using these yearly cost estimates, over 20 years $25.1 million in man-hours would be spent on
applying for and processing special conditions, exemptions, and ELOS. However under the proposed
rule, the FAA believes that the need to demonstrate compliance through special conditions, exemptions,
or ELOS would largely be eliminated. Instead new products will simply need to demonstrate compliance
by following consensus standards acceptable to the Administrator, or by submitting their own novel
demonstrations of compliance. As a conservative estimate, the FAA estimates that special conditions,
exemptions, and ELOS would be reduced by half for a savings to the FAA and applicant of roughly
181
$12.6 million ($5.8 million present value). Savings by year is shown in the chart below. The FAA asks
for comment regarding the amount of reduction in the alternative means of compliance.
In addition to this savings, there would also be additional paperwork burden associated with
proposed § 23.200. As proposed, this provision could result in a change to a limitation or a performance
number in the flight manual, which would reqire an update to the training courseware or flight manual.
Industry believes that this proposed change could cost from $100,000 to $150,000. Therefore, the FAA
uses $125,000 (($100,000 + $150,000)/2) as an average cost for this proposed change.
There would also be additional paperwork associated with this requirement that is not part of the
costs discussed above. The FAA estimates the paperwork costs for these proposed provisions by
multiplying the number of hours the FAA estimates for each page of paperwork, by the number of pages
for the training courseware, or flight manual, by the hourly rate of the person responsible for the update.
The Small Aircraft Directorate of the FAA provided average hourly times and the number of additional
pages of paperwork the proposal would add. The FAA estimates that this section would add a total of
four pages to the training courseware and flight manual. The FAA also estimates that it would take a
part 23 certification engineer eight hours to complete the one page required for each new type
certification. The eight hours to complete a page includes the research, coordination, and review each
document requires. Therefore, the FAA estimates the total paperwork costs for proposed controllability
section would be about $1,939 (8 hours * 4 pages * $60.58 per hour) in 2014 dollars.
The FAA is expecting part 23 airplane manufacturers to update their engineering procedures
manuals to reflect the changes from this proposed rulemaking. However, most of the engineering
procedures manuals are not written around the requirements of part 23, but around the requirements of
part 21. Since the part 23 changes would have minimal impact on the part 21 requirements, there should
be little change in the engineering procedures manuals. Conversations with industry indicate that there
182
may need to be some changes to the engineering manuals to describe how the accepted means of
compliance must be related to the regulations. Depending on the complexity of each company’s manual,
industry estimates that these changes could run from about $50,000 up to $200,000. This would be a
one-time cost per new type certification.
Since the FAA is unable to determine the complexity of each company’s manual, we assume that
the manufacturers of the two new part 23 reciprocating engine airplane type certifications, discussed in
the “Fleet Discussion” section of the regulatory impact analysis, would spend $50,000 to make the
changes to the engineering manual. We also assume that the one new part 23 turboprop airplane
certification and the two new part 23 turbojet airplane certifications, discussed in the “Fleet Discussion”
section, would use the more complex and costly approach of $200,000.
The FAA notes that either the simple approach or the more complex approach to updating the
manuals could also either take place in-house or could be contracted out to a consultant.
Table 10 shows the total costs for the proposed changes to the controllability section.
Table 10. Estimate Costs for Updating Engineering Manuals (2014 $)
Airplane
Recip
Turboprop
Turbojet
Number of Estimated
New Type Certificates
2
1
2
Simple
Approach
$50,000
$0
$0
Total
*These numbers are subject to rounding error.
Complex
Approach
$0
$200,000
$200,000
Total
$100,000
$200,000
$400,000
$700,000
F. International Compatibility and Cooperation
In keeping with U.S. obligations under the Convention on International Civil Aviation, it is
FAA policy to conform to International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has reviewed the corresponding
ICAO Standards and Recommended Practices and has identified the following differences with these
proposed regulations. The ICAO Standards for small airplanes use weight and propulsion to differentiate
183
between some requirements. The proposed regulations use certification levels and performance to
differentiate between some requirements. Furthermore, part 23 will still allow the certification of
airplanes up to 19,000 pounds. If this proposal is adopted, the FAA intends to file these differences with
ICAO. Executive Order (EO) 13609, Promoting International Regulatory Cooperation, (77 FR 26413,
May 4, 2012) promotes international regulatory cooperation to meet shared challenges involving health,
safety, labor, security, environmental, and other issues and reduce, eliminate, or prevent unnecessary
differences in regulatory requirements. The FAA has analyzed this action under the policy and agency
responsibilities of Executive Order 13609, Promoting International Regulatory Cooperation. The agency
has determined that this action would eliminate differences between U.S. aviation standards and those of
other CAAs by aligning the revised part 23 standards with the new CS-23 standards that are being
developed concurrently by EASA. Several other CAAs are participating in this effort and intend to
either adopt the new part 23 or CS-23 regulations or revise their airworthiness standards to align with
these new regulations.
The Part 23 Reorganization ARC included participants from several foreign CAAs and international
members from almost every GA manufacturer of both airplanes and avionics. It also included several
Light-Sport Aircraft manufacturers who are interested in certificating their products using the
airworthiness standards contained in part 23. The rulemaking and means of compliance documents are
international efforts. Authorities from Europe, Canada, Brazil, China, and New Zealand all are working
to produce similar rules. These rules, while not identical, are intended to allow the use of the same set of
industry developed means of compliance. Industry has told that FAA that it is very costly to address the
differences that some contrived means of compliance imposes. If there is substantial agreement between
the major CAAs to use the same industry means of compliance document, then U.S. manufactures
expect a significant saving for exporting their products.
184
Furthermore, this project is a harmonization project between the FAA and EASA.
EASA has worked a parallel rulemaking program for CS-23. The FAA provided comments to the
EASA A-NPA The EASA and other authorities will have an opportunity to comment on this NPRM
when it is published. These efforts will allow the FAA, EASA and other authorities to work toward a
harmonized set of regulations when the final rules are published.
G. Environmental Analysis
FAA Order 1050.1F identifies FAA actions that are categorically excluded from preparation of
an environmental assessment or environmental impact statement under the National Environmental
Policy Act in the absence of extraordinary circumstances. The FAA has determined this rulemaking
action qualifies for the categorical exclusion identified in paragraph 5-6.6 and involves no extraordinary
circumstances.
H. Regulations Affecting Intrastate Aviation in Alaska
Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 3213) requires the
Administrator, when modifying 14 CFR regulations in a manner affecting intrastate aviation in Alaska,
to consider the extent to which Alaska is not served by transportation modes other than aviation, and to
establish appropriate regulatory distinctions. Because this proposed rule would apply to GA
airworthiness standards, it could, if adopted, affect intrastate aviation in Alaska. The FAA, therefore,
specifically requests comments on whether there is justification for applying the proposed rule
differently in intrastate operations in Alaska.
VIII. Executive Order Determination
A. Executive Order 13132, Federalism
The FAA has analyzed this proposed rule under the principles and criteria of Executive Order
13132, Federalism. The agency has determined that this action would not have a substantial direct effect
185
on the States, or the relationship between the Federal Government and the States, or on the distribution
of power and responsibilities among the various levels of government, and, therefore, would not have
Federalism implications.
B. Executive Order 13211, Regulations that Significantly Affect Energy Supply, Distribution, or Use
The FAA analyzed this proposed rule under Executive Order 13211, Actions Concerning
Regulations that Significantly Affect Energy Supply, Distribution, or Use (May 18, 2001). The agency
has determined that it would not be a “significant energy” action under the executive order and would
not be likely to have a significant adverse effect on the supply, distribution, or use of energy.
IX. Additional Information
A. Comments Invited
The FAA invites interested persons to participate in this rulemaking by submitting written
comments, data, or views. The agency also invites comments relating to the economic, environmental,
energy, or federalism impacts that might result from adopting the proposals in this document. The most
helpful comments reference a specific portion of the proposal, explain the reason for any recommended
change, and include supporting data. To ensure the docket does not contain duplicate comments,
commenters should send only one copy of written comments, or if comments are filed electronically,
commenters should submit only one time.
The FAA will file in the docket all comments it receives, as well as a report summarizing each
substantive public contact with FAA personnel concerning this proposed rulemaking. Before acting on
this proposal, the FAA will consider all comments it receives on or before the closing date for
comments. The FAA will consider comments filed after the comment period has closed if it is possible
to do so without incurring expense or delay. The agency may change this proposal in light of the
comments it receives.
186
Proprietary or Confidential Business Information: Commenters should not file proprietary or
confidential business information in the docket. Such information must be sent or delivered directly to
the person identified in the FOR FURTHER INFORMATION CONTACT section of this document, and
marked as proprietary or confidential. If submitting information on a disk or CD ROM, mark the outside
of the disk or CD ROM, and identify electronically within the disk or CD ROM the specific information
that is proprietary or confidential.
Under 14 CFR 11.35(b), if the FAA is aware of proprietary information filed with a comment,
the agency does not place it in the docket. It is held in a separate file to which the public does not have
access, and the FAA places a note in the docket that it has received it. If the FAA receives a request to
examine or copy this information, it treats it as any other request under the Freedom of Information Act
(5 U.S.C. 552). The FAA processes such a request under Department of Transportation procedures
found in 49 CFR part 7.
B. Availability of Rulemaking Documents
An electronic copy of rulemaking documents may be obtained from the Internet by—
1. Searching the Federal eRulemaking Portal (http://www.regulations.gov);
2. Visiting the FAA’s Regulations and Policies web page at
http://www.faa.gov/regulations_policies or
3. Accessing the Government Printing Office’s web page at http://www.gpo.gov/fdsys/.
Copies may also be obtained by sending a request to the Federal Aviation Administration, Office
of Rulemaking, ARM-1, 800 Independence Avenue SW., Washington, DC 20591, or by calling
(202) 267-9680. Commenters must identify the docket or notice number of this rulemaking.
187
All documents the FAA considered in developing this proposed rule, including economic
analyses and technical reports, may be accessed from the Internet through the Federal eRulemaking
Portal referenced in item (1) above.
Appendix 1 to the Preamble—Current to Proposed Regulations Cross-Reference Table
The below cross-reference table is intended to permit easy access from proposed to current regulations.
The preamble is organized topical, section-by-section, proposed to current regulations. This table should
assist the reader in following the section discussions contained in the preamble.
Current
Section
Title
Proposed Section
Proposed Title
Subpart A—General
23.1
Applicability
23.2
Special retroactive
requirements
--
23.3
Airplane categories
23.5
Certification of normal
category airplanes
23.10
Accepted means of
compliance
--
23.1
--
Applicability
--Deleted--
Subpart B—Flight
23.21
Proof of compliance
23.100
Weight and center of gravity
23.23
Load distribution limits
23.100
Weight and center of gravity
23.25
Weight limits
23.100
Weight and center of gravity
23.29
Empty weight and
corresponding center of
gravity
23.100
Weight and center of gravity
23.31
Removable ballast
23.100
Weight and center of gravity
23.33
Propeller speed and
pitch limits
23.900
Powerplant installation
188
Current
Section
Title
Proposed Section
23.45
Performance - General
23.105
Performance
23.49
Stalling speed
23.110
Stall Speed
23.51
Takeoff speeds
23.115
Takeoff performance
23.53
Takeoff performance
23.115
Takeoff performance
23.55
Accelerate-stop
distance
23.115
Takeoff performance
23.57
Takeoff path
23.115
Takeoff performance
23.59
Takeoff distance and
takeoff run
23.115
Takeoff performance
23.61
Takeoff flight path
23.115
Takeoff performance
23.63
Climb: General
23.120
Climb
23.65
Climb: All engines
operating
23.120
Climb
23.66
Takeoff climb: one
engine inoperative
23.125
Climb
23.67
Climb: One engine
inoperative
23.120
Climb
23.69
Enroute climb/descent
23.125
Climb
23.71
Glide: single engine
airplanes
23.125
Climb
23.73
Reference landing
approach speed
23.130
Landing
23.75
Landing distance
23.130
Landing
23.77
Balked landing
23.120
Climb
189
Proposed Title
Current
Section
23.141
23.143
Title
Flight Characteristics General
Controllability and
Maneuverability General
Proposed Section
Proposed Title
23.200
Controllability
23.200
Controllability
23.145
Longitudinal control
23.200
Controllability
23.147
Directional and lateral
control
23.200
Controllability
23.149
Minimum control speed
23.200
Controllability
23.151
Acrobatic maneuvers
23.200
Controllability
23.153
Control during landings
23.200
Controllability
23.155
Elevator control force
in maneuvers
23.200
Controllability
23.157
Rate of roll
23.200
Controllability
23.161
Trim
23.205
Trim
23.171
Stability – General
23.210
Stability
23.173
Static longitudinal
stability
23.210
Stability
23.175
Demonstration of static
longitudinal stability
23.210
Stability
23.177
Static directional and
lateral stability
23.210
Stability
23.179
Instrument stick force
measurements
23.210
Stability
23.181
Dynamic stability
23.210
Stability
23.201
Wings level stall
23.215
Stall characteristics, stall
warning, and spins
190
Current
Section
Title
Proposed Section
Proposed Title
23.203
Turning Flight and
accelerated turning
stalls
23.215
Stall characteristics, stall
warning, and spins
23.207
Stall Warning
23.215
Stall characteristics, stall
warning, and spins
23.221
Spinning
23.215
Stall characteristics, stall
warning, and spins
23.231
Longitudinal stability
and control
23.220
Ground handling
23.233
Directional stability
and control
23.220
Ground handling
23.235
Operation on unpaved
surfaces
23.220
Ground handling
23.237
Operation on water
23.220
Ground handling
23.239
Spray characteristics
23.220
Ground handling
23.251
Vibration and buffeting
23.225
Vibration, buffeting, and
high-speed characteristics
23.253
High speed
characteristics
23.225
Vibration, buffeting, and
high-speed characteristics
23.255
Out of trim
characteristics
23.225
Vibration, buffeting, and
high-speed characteristics
23.230
Performance and flight
characteristics requirements
for flight in icing conditions
--
--
Subpart C – Structure
23.301
Loads
23.310, 23.330
Structural design loads, Limit
and ultimate loads
(a)
--
23.330
Limit and ultimate loads
(b)
--
23.310
Structural design loads
(c)
--
23.310
Structural design loads
191
Current
Section
Title
Proposed Section
(d)
--
23.310
Structural design loads
23.302
Canard or tandem wing
configurations
23.310
Structural design loads
23.303
Factors of safety
23.330
Limit and ultimate loads
23.305
Strength and
deformation
23.400
Structural strength
--
23.305
Interaction of systems and
structures
--
Proposed Title
23.307
Proof of structure
23.400
Structure strength
23.321
Flight Loads - General
23.310
Structural design loads
(a)
--
23.310
Structural design loads
(b)
--
23.300
Structural design envelope
(c)
--
23.300
Structural design envelope
23.331
Symmetrical flight
conditions
23.310
Structural design loads
23.333
Flight envelope
23.300
Structural design envelope
(a)
--
23.300
Structural design envelope
(b)
--
23.300
Structural design envelope
(c)
--
23.315
Flight load conditions
(d)
--
23.300
Structural design envelope
23.300
Structural design envelope
23.335
Design airspeeds
192
Current
Section
23.337
Title
Limit maneuvering
load factors
Proposed Section
Proposed Title
23.300
Flight load conditions
(a)
--
23.300
Structural design envelope
(b)
--
23.300
Structural design envelope
(c)
--
Means of Compliance
--
23.341
Gust load factors
23.315
Flight load conditions
23.343
Design fuel loads
23.300
Structural design envelope
(a)
--
23.300
Structural design envelope
(b)
--
23.300
Structural design envelope
(c)
--
Means of Compliance
--
23.345
High lift devices
23.325
Component loading
conditions
23.347
Unsymmetrical flight
loads
23.315
Flight load conditions
23.349
Rolling conditions
23.315
Flight load conditions
23.351
Yawing conditions
23.315
Flight load conditions
23.361
Engine torque
23.325
Component loading
conditions
23.363
Side load on engine
mount
23.325
Component loading
conditions
23.365
Pressurized cabin loads
23.325
Flight load conditions
(e)
--
23.405
Structural durability
193
Current
Section
Title
Proposed Section
Proposed Title
23.367
Unsymmetrical loads
due to engine failure
23.369
Rear lift truss
23.371
Gyroscopic and
aerodynamic loads
23.325
Component loading
conditions
23.373
Speed control devices
23.325
Component loading
conditions
23.391
Control surface loads
23.325
Component loading
conditions
23.393
Loads parallel to hinge
line
23.325
Component loading
conditions
23.395
Control system loads
23.325
Component loading
conditions
23.397
Limit control forces
and torques
23.325
Component loading
conditions
23.399
Dual control system
23.325
Component loading
conditions
23.405
Secondary control
system
23.325
Component loading
conditions
23.407
Trim tab effects
23.325
Component loading
conditions
23.409
Tabs
23.325
Component loading
conditions
23.415
Ground gust conditions
23.325
Component loading
conditions
23.421
Balancing loads
23.423
Maneuvering loads
23.315
Flight load conditions
23.425
Gust loads
23.315
Flight load conditions
23.427
Unsymmetrical loads
due to engine failure
23.315
Flight load conditions
23.315
Means of Compliance
Means of Compliance
194
Flight load conditions
--
--
Current
Section
Title
Proposed Section
Proposed Title
23.441
Maneuvering loads
23.315
Flight load conditions
23.443
Gust loads
23.315
Flight load conditions
23.445
Outboard fins or
winglets
23.455
Ailerons
23.325
Component loading
conditions
23.459
Special devices
23.325
Component loading
conditions
23.471
Ground Loads General
23.320
Ground and water load
conditions
23.473
Ground load conditions
and assumptions
23.320
Ground and water load
conditions
23.477
Landing gear
arrangement
23.320
Ground and water load
conditions
23.479
level landing conditions
23.320
Ground and water load
conditions
23.481
Tail down landing
conditions
23.320
Ground and water load
conditions
23.483
One-wheel landing
conditions
23.320
Ground and water load
conditions
23.485
Side load conditions
23.320
Ground and water load
conditions
23.493
Braked roll conditions
23.320
Ground and water load
conditions
23.320
Ground and water load
conditions
23.320
Ground and water load
conditions
23.320
Ground and water load
conditions
23.320
Ground and water load
conditions
23.497
23.499
23.505
23.507
Supplementary
conditions for tail
wheels
Supplementary
conditions for nose
wheels
Supplementary
conditions for skiplanes
Jacking loads
Means of Compliance
195
--
Current
Section
Title
Proposed Section
Proposed Title
23.509
Towing loads
23.320
Ground and water load
conditions
23.511
Ground load:
unsymmetrical loads on
multiple-wheel units
23.320
Ground and water load
conditions
23.521
Water load conditions
23.320
Ground and water load
conditions
23.523
Design weights and
center of gravity
positions
23.320
Ground and water load
conditions
23.525
Application of loads
23.320
Ground and water load
conditions
23.527
Hull and main float
load factors
23.320
Ground and water load
conditions
23.529
Hull and main float
landing conditions
23.320
Ground and water load
conditions
23.531
Hull and main float
takeoff conditions
23.320
Ground and water load
conditions
23.533
Hull and main float
bottom pressures
23.320
Ground and water load
conditions
23.535
Auxiliary float loads
23.320
Ground and water load
conditions
23.537
Seawing loads
23.320
Ground and water load
conditions
23.561
Emergency Landing
Conditions - General
23.600
Emergency conditions
23.562
Emergency landing
dynamic conditions
23.600
Emergency conditions
23.405
Structural durability
23.405
Structural durability
23.405
Structural durability
23.571
23.572
23.573
Metallic pressurized
cabin structures
Metallic wing,
empennage, and
associated structures
Damage tolerance and
fatigue evaluation of
structure
196
Current
Section
23.574
23.575
Title
Metallic damage
tolerance and fatigue
evaluation of commuter
category airplanes
Inspections and other
procedures
Proposed Section
Proposed Title
23.405
Structural durability
23.405
Structural durability
Subpart D - Design and Construction
23.601
General
23.500
Structural design
23.603
Materials and
workmanship
23.500
Structural design
23.605
Fabrication methods
23.510
Materials and processes
23.607
Fasteners
23.505
Protection of structure
23.609
Protection of Structure
23.505
Protection of structure
23.611
Accessibility
23.505
Protection of structure
23.613
Material strength
properties and design
values
23.510
Materials and processes
23.619
Special factors
23.515
Special factors of safety
23.621
Casting factors
23.515
Special factors of safety
23.623
Bearing factors
23.515
Special factors of safety
23.625
Fitting factors
23.515
Special factors of safety
23.627
Fatigue strength
23.405
Structural durability
23.629
Flutter
23.410
Aeroelasticity
23.641
Proof of strength
Means of Compliance
197
--
Current
Section
Title
Proposed Section
Proposed Title
23.651
Proof of strength
Means of Compliance
--
23.655
Installation
Means of Compliance
--
23.657
Hinges
23.515
Special factors of safety
23.659
Mass balance
23.315
Flight load conditions
23.671
Control Surfaces General
--
--
(a)
--
23.500
Structural design
(b)
--
23.1305
Function and installation
23.672
Stability augmentation
and automatic and
power-operated
systems
23.1305
Function and installation
23.673
Primary flight controls
23.1305
Function and installation
23.675
Stops
23.1305
Function and installation
23.677
Trim systems
--
--
(a)
--
23.700
Flight control systems
(b)
--
23.700
Flight control systems
(c)
--
23.410
Aeroelasticity
(d)
--
23.700
Flight control systems
23.1305
Function and installation
23.679
Control system locks
198
Current
Section
Title
Proposed Section
23.681(a)
Limit load static tests
23.325(b)
23.681(b)
Limit load static tests
23.515
23.683
Operation tests
23.685(a), (b),
Control system details
(c)
23.685(d)
Control system details
Proposed Title
Component loading
conditions
Special factors of safety
23.500(d)
Structural design
23.500(d)
Structural design
23.1305
23.687
Spring devices
23.410 and 23.500
23.689
Cable systems
--
Function and installation
Aeroelasticity and Structural
design
--
(a)
--
23.700
(b)
--
23.325(b), 23.500(d)
Component loading
conditions, Structural design
(c)
--
23.325(b), 23.500(d)
Component loading
conditions, Structural design
(d)
--
23.325(b), 23.500(d)
Component loading
conditions, Structural design
(e)
--
23.325(b), 23.500(d)
Component loading
conditions, Structural design
(f)
--
23.700
199
Flight control systems
Flight control systems
Current
Section
23.691
Title
Proposed Section
Proposed Title
--
--
Artificial stall barrier
system
(a)
--
23.700
Flight control systems
(b)
--
23.700
Flight control systems
(c)
--
23.1305
Function and installation
(d)
--
23.700
Flight control systems
(e)
--
23.700
Flight control systems
(f)
--
23.700
Flight control systems
(g)
--
23.1315
Equipment, systems and
Installations
23.515
Special factors of safety
23.693
Joints
23.697
Wing flap controls
--
--
(a)
--
23.700
Flight control systems
(b) and (c)
--
23.200
Controllability
23.1500
Flightcrew interface
23.699
Wing flap position
indicator
23.701
Flap interconnection
23.703
Takeoff warning
system
Means Of Compliance
--
--
--
(a)
--
23.700
Flight control systems
(b)
--
23.700
Flight control systems
200
Current
Section
Title
Proposed Section
Proposed Title
(c)
--
Definition
--
23.910
Powerplant installation hazard
assessment
23.721
General
23.723
Shock absorption tests
23.725
Limit drop tests
23.726
Ground load dynamic
tests
Means Of Compliance
23.727
Reserve energy
absorption drop tests
Means Of Compliance
23.729
Landing gear extension
and retraction system
--
(a)
--
23.705
Landing gear systems
(b)
--
23.705
Landing gear systems
(c)
--
23.705
Landing gear systems
(d)
--
Means Of Compliance
(e)
--
23.705
(f)
--
23.1315
Equipment, systems and
installation
(g)
--
Means Of Compliance
--
23.731
Wheels
23.733
Tires
(a)
Means Of Compliance
Means Of Compliance
23.705
---
23.705
201
------
-Landing gear systems
Landing gear systems
-Landing gear systems
Current
Section
Title
(b)
--
(c)
--
23.735
Brakes
Proposed Section
Means Of Compliance
Means Of Compliance
23.705
23.705
Proposed Title
----
(a)
--
(1)
--
(2)
--
(b)
--
23.705
(c)
--
Means Of Compliance
(d)
--
1315
Equipment, systems and
installation
(e)
--
705
Landing gear systems
(1)
--
Means Of Compliance
--
(2)
--
Means Of Compliance
--
Means Of Compliance
Means Of Compliance
Landing gear systems
--Landing gear systems
--
23.737
Skis
23.705
Landing gear systems
23.745
Nose/Tail wheel
steering
23.1500
Flightcrew interface
23.751
Main float buoyancy
--
(a)
--
710
(b)
--
Means Of Compliance
202
-Buoyancy for seaplanes and
amphibians
--
Current
Section
Title
Proposed Section
Proposed Title
23.753
Main float design
23.320
Ground and water load
conditions
23.755
Hulls
23.710
Buoyancy for seaplanes and
amphibians
23.757
Auxiliary floats
23.710
Buoyancy for seaplanes and
amphibians
23.771
Pilot compartment
--
--
(a)
--
23.1500
(b)
--
755
Occupant physical
environment
(c)
--
755
Occupant physical
environment
23.773
Pilot compartment view
--
(a)
--
1500
(b)
--
23.755
23.775
Windshields and
windows
--
Flightcrew interface
-Flightcrew interface
Occupant physical
environment
--
(a), (b), (c),
(d)
--
23.755
(e)
--
Means Of Compliance
(f)
--
23.1405
(g)
--
Means Of Compliance
(h)
--
23.755
Occupant physical
environment
23.1500
Flightcrew interface
23.777
Cockpit controls
203
Occupant physical
environment
-Flight in icing conditions
--
Current
Section
Title
Proposed Section
Proposed Title
23.779
Motion and effect of
cockpit controls
23.1500
Flightcrew interface
23.781
Cockpit control knob
shape
23.1500
Flightcrew interface
23.783
Doors
--
(a), (b), (c),
(d)
--
23.750
(e), (f), (g)
--
Means Of Compliance
-Means of egress and
emergency exits
--
23.785
Seats, berths, litters,
safety belts, and
shoulder harnesses
23.515 and 23.600
23.787
Baggage and cargo
compartments
23.600(e)
Emergency landing
conditions
23.791
Passenger information
signs
23.755
Occupant physical
environment
23.803
Emergency evacuation
--
(a)
--
23.750
(b)
--
Means Of Compliance
23.805
Flightcrew emergency
exits
23.807
Emergency exits
(a)(3), (b)(1),
(c), (d)(1),
(d)(4)
Balance of
23.807
23.811
23.750
Special factors of safety,
Emergency landing
conditions
-Means of egress and
emergency exits
-Means of egress and
emergency exits
--
--
--
Means Of Compliance
--
--
23.750
Means of egress and
emergency exits
23.750
Means of egress and
emergency exits
Emergency exit
marking
204
Current
Section
Title
Proposed Section
23.750
Proposed Title
Means of egress and
emergency exits
23.812
Emergency lighting
23.813
Emergency exit access
--
(a)
--
23.750
(b)
--
Means Of Compliance
CS-VLA 853
--
23.750
Means of egress and
emergency exits
-Means of egress and
emergency exits
--
23.815
Width of aisle
23.750
Means of egress and
emergency exits
23.831
Ventilation
23.755
Occupant physical
environment
Pressurized cabins
23.755
Occupant physical
environment
23.841(a),
(b)(6), (c) ,(d)
(b)(1) through
(5) and (7)
--
Means Of Compliance
23.843
Pressurization tests
23.755
23.851
Fire extinguishers
--
-Occupant physical
environment
-Fire protection outside
designated fire zones
(a) and (b)
--
23.800
(c)
--
Means Of Compliance
--
--
--
23.853
(a)
(b)(c) and
(d)(1)(2)
(d)(3)(i),
(d)(3)(iii),
(d)(3)(iv)
Passenger and crew
compartment interiors
--
23.800
--
Means Of Compliance
--
23.800
205
Fire protection outside
designated fire zones
-Fire protection outside
designated fire zones
Current
Section
Title
Proposed Section
(e)
--
23.800
Fire protection outside
designated fire zones
(f)
--
23.800
Fire protection outside
designated fire zones
23.800
Fire protection outside
designated fire zones
23.800
Fire protection outside
designated fire zones
23.855
23.856
Cargo and baggage
compartment fire
protection
Thermal/acoustic
insulation materials
Proposed Title
23.859
Combustion heater fire
protection
--
(a)
--
23.800
(b) thru (i)
--
Means Of Compliance
--
--
--
23.863
Flammable fluid fire
protection
-Fire protection outside
designated fire zones
(a) and (d)
--
23.800
Fire protection outside
designated fire zones
(b) and (c)
--
Means Of Compliance
Fire protection outside
designated fire zones
23.865
23.867
Fire protection of flight
controls, engine
mounts, and other flight
structure
Electrical bonding and
protection against
lightning and static
electricity
23.805
--
Fire protection in designated
fire zones
--
(a) and (c)
--
23.810
Lightning protection of
structure
(b)
--
23.1320
Electrical and electronic
system lightning protection
23.871
Leveling means
Means Of Compliance
Subpart E – Powerplant
206
--
Current
Section
23.901
Title
Installation
Proposed Section
23.900(c)
Proposed Title
Powerplant Installation
(a), (b), (f)
--
23.900(b)
--
(c)
--
23.900(b)
--
(d) and (e)
--
23.900(b)
Note: In addition to 900(b)
these rules are covered under
Part 33.63, 76, 77 and 78.
--
---
23.903
Engines
(a)
--
23.900(c)
(a)(2)
--
23.940(b)
(b)(c)
--
23.910 and 23.920
(b)(1)
--
23.405(d)
(d) thru (g)
--
23.925
Powerplant operational
characteristics
23.915
Automatic power control
systems
23.904
Automatic power
reserve system
23.905
Propellers
Powerplant ice protection
Powerplant installation hazard
assessment; Reversing
systems
Structural durability
--
-Powerplant installation hazard
assessment
(a)
--
23.910(a)
(b), (d), (g)
--
--
(c)
--
23.905
Propeller installation
(e)
--
23.940
Powerplant ice protection
(f)
--
23.905
Propeller installation
207
Note: Intent covered under
part 35
Current
Section
Title
Proposed Section
Proposed Title
(h)
--
23.910
Powerplant installation hazard
assessment
23.907
Propeller vibration and
fatigue
--
23.909
Turbocharger systems
--
Note: Intent covered under
part 35
--
(a) and (c)
--
23.900
Powerplant installation
(b), (d), (e)
--
23.910
Powerplant installation hazard
assessment
23.925
Propeller clearance
23.905(c)
23.929
Engine installation ice
protection
23.940
23.933
Reversing systems
23.920
Installation
Powerplant ice protection
--
(a)
--
23.920
Reversing systems
(b)
--
23.920
Reversing systems
23.934
Turbojet and turbofan
engine thrust reverser
systems tests
23.920
Note: In addition to § 23.920,
this rule is covered under
§ 33.97.
23.937
Turbopropeller-drag
limiting systems
23.920
--
(a)
--
23.920
(b)
--
23.920
Reversing systems
Reversing systems
23.939
Powerplant operating
characteristics
23.925
In addition to 925 this rule is
covered under Part 33,
subpart D and F - Block Tests
23.943
Negative acceleration
23.925
Operational characteristics
208
Current
Section
23.951
Title
Fuel System - General
Proposed Section
Proposed Title
23.930(a)(3)
--
(a) and (b)
--
23.930(a)(3)
(c)
--
23.930(a)(3)
(d)
--
23.930(a)(3)
Fuel systems
-Intent covered under Part 34
23.953
Fuel system
independence
23.930
Fuel systems
23.954
Fuel system lightning
protection
23.930
Fuel systems
23.955
Fuel flow
23.930
Fuel systems
23.957
Flow between
interconnected tanks
23.930(a)(7)
Fuel systems
(a)
--
23.930(a)(7)
--
(b)
--
23.930(a)(7)
--
23.959
Unusable fuel supply
23.930(c)
23.961
Fuel system hot
weather operation
23.930(a)(3)
23.963
Fuel tank: general
--
Hazard assessment
Fuel systems
--
(a), (d), (e)
--
23.930(b)(4)
Fuel systems
(b) and (c)
--
23.930(b)(6)
--
23.965
Fuel tank tests
23.930(b)(1)
--
23.967
Fuel tank installation
23.930(b)(6)
--
209
Current
Section
Title
Proposed Section
Proposed Title
23.969
Fuel tank expansion
space
23.930(b)(6)
--
23.971
Fuel tank sump
23.930(b)(6)
--
23.973
Fuel tank filler
connection
23.930(b)(6)
--
23.975
Fuel tank vents and
carburetor vapor vents
23.930(b)(6)
--
(a)(1)
--
23.940
23.977
Fuel tank outlet
23.930(b)(6)
23.979
Pressure fueling
systems
23.930(d)
Powerplant ice protection
Fuel systems
--
(a) and (b)
--
23.930(d)
Fuel systems
(c) and (d)
--
23.930(d)
Hazard assessment
23.991
Fuel pumps
23.930(a)(8)
--
(a), (b), (c)
--
23.930(a)(8)
(d)
--
23.910
Powerplant installation hazard
assessment
23.930
--
23.993
Fuel system lines and
fittings
23.994
Fuel system
components
23.995
Fuel valves and
controls
23.930(a)(7)
23.930(d)
(a)
--
23.930(d)
(b) thru (g)
--
23.930(d)
210
Fuel systems
Hazard assessment
-Powerplant installation
--
Current
Section
23.997
Title
Fuel strainer or filter
Proposed Section
Proposed Title
23.930(a)
--
(a) thru (d)
--
23.930(a)(6)
(e)
--
23.950
Fuel systems
Powerplant ice protection
23.999
Fuel system drains
23.930(a)(4)
Fuel systems
23.1001
Fuel jettisoning system
23.930(b)(5)
(a)
--
23.930(b)(5)
(b) thru (g)
--
23.930(b)(5)
--
(h)
--
23.910
Powerplant installation hazard
assessment
-Fuel systems
23.1011
General
23.935
Intent covered under Part 33
23.1013
Oil tanks
23.935(b)(1)
Intent covered under Part 33
23.1015
Oil tank tests
23.935(b)(1)
Intent covered under Part 33
23.1017
Oil lines and fittings
23.935(b)(1)
Intent covered under Part 33
23.1019
Oil strainer or filter
23.935(b)(2)
Intent covered under Part 33
23.1021
Oil system drains
23.935(b)(2)
Intent covered under Part 33
23.1023
Oil radiators
23.935(b)(1)
Intent covered under Part 33
23.1027
Propeller feathering
system
23.935(b)(2)
Hazard assessment
23.1041
Cooling – General
23.940(a)
211
Intent covered under Part 33
Current
Section
Title
Proposed Section
Proposed Title
23.1043
Cooling tests
23.940(a)
Intent covered under Part 33
23.1045
Cooling test procedures
for turbine engine
powered airplanes
23.940(a)
Intent covered under Part 33
23.1047
Cooling test procedures
for reciprocating engine
powered airplanes
23.940(a)
Intent covered under Part 33
23.1061
Installation
23.940(b)
Intent covered under Part 33
23.1063
Coolant tank tests
23.940(b)
Intent covered under Part 33
23.1091
Air induction system
23.945(a)
Intent covered under Part 33
23.1093
Induction system icing
protection
23.940
Powerplant ice protection
23.1095
Carburetor deicing
fluid flow rate
23.940
Powerplant ice protection
23.940
Powerplant ice protection
23.940
Powerplant ice protection
23.1097
23.1099
23.1101
Carburetor deicing
fluid system capacity
Carburetor deicing
fluid system detail
design
Induction air preheater
design
23.935
(a)
--
23.935
(b) and (c)
--
23.935
23.1103
Induction system ducts
23.935
23.1105
Induction system
screens
23.935
23.1107
Induction system filters
23.935
212
-Powerplant induction and
exhaust systems
-Powerplant induction and
exhaust systems
-Powerplant induction and
exhaust systems
Current
Section
Title
Proposed Section
Proposed Title
23.1109
Turbocharger bleed air
system
23.910
--
23.1111
Turbine engine bleed
air system
23.910
--
(a) and (c)
--
23.910
(b)
--
23.910
--
23.935
--
23.1121
Exhaust System General
Hazard assessment
(a) thru (g)
--
23.935
Powerplant induction and
exhaust systems
(h)
--
23.910
Hazard assessment
Hazard assessment
23.1123
Exhaust system
23.910
23.1125
Exhaust heat
exchangers
23.910
(a)
--
23.910
(b)
--
23.910
--
23.1505(b)
--
23.910
Powerplant installation hazard
assessment
23.1141
Powerplant controls:
general (a)(c)(g)
(b)(d)(e) and (f)
-Hazard assessment
23.1142
Auxiliary power unit
controls
23.1500(b)
--
23.1143
Engine controls
23.1500(b)
--
23.1145
Ignition switches
23.1500(b)
--
23.1147
Mixture controls
23.1500(b)
--
213
Current
Section
Title
Proposed Section
Proposed Title
23.1149
Propeller speed and
pitch controls
23.1500(b)
--
23.1153
Propeller feathering
controls
23.1500(b)
--
23.1155
Turbine engine reverse
thrust and propeller
pitch settings below the
flight regime
23.1157
Carburetor air
temperature controls
23.1500(b)
--
23.1163
Powerplant accessories
23.910(a)
Powerplant installation hazard
assessment
(a), (c), (e)
--
23.910(a)
--
(b) and (d)
--
23.910(a)
--
23.1165
Engine ignition systems
Means Of Compliance
--
23.1181
Designated fire zones:
regions included
23.1000(a)
23.1182
Nacelle areas behind
firewalls
23.1000(b)
--
23.1183
Lines, fittings, and
components
23.1000(b)
--
23.1189
Shutoff means
23.1000(c)
--
23.1191
Firewalls
23.1000(d)
--
23.910 and 23.1500(b) Hazard assessment
Powerplant fire protection
(a) thru (e),
(g), (h)
--
23.1000(d)
--
(f)
--
23.910
Powerplant installation hazard
assessment
23.1000(d)
--
23.1192
Engine accessory
compartment
diaphragm
214
Current
Section
23.1193
Title
Cowling and nacelle
Proposed Section
Proposed Title
23.1000(d)
---
(a) thru (e)
--
23.1000(d)
(f) and (g)
--
23.1000(d)
Hazard assessment
23.1195
Fire extinguishing
systems
23.1000(e)
--
23.1197
Fire extinguishing
agents
23.1000(e)
--
23.1199
Extinguishing agent
containers
23.1000(e)
--
23.1201
Fire extinguishing
system materials
23.1000(e)
--
(a)
--
23.1000(e)
(b)
--
23.1000(e)
--
23.1000(f)
---
23.1203
Fire detector system
(a), (d), (e)
--
23.1000(f)
(b) and (c)
--
23.1000(f)
Hazard assessment
Hazard assessment
Subpart F – Equipment
23.1301
Function and
installation
--
-Airplane level systems
requirements;
Function and installation
(a)
--
23.1300(a) and
23.1305(a)
(b)
--
23.1305(a)(3)
Function and installation
(c)
--
23.1305(a)(2)
Function and installation
215
Current
Section
Title
23.1303
Flight and navigation
instruments
23.1305
Powerplant instruments
23.1306
Electrical and
electronic system
lightning protection
23.1307
23.1308
23.1309
Miscellaneous
equipment
High-Intensity Radiated
Fields (HIRF)
protection
Equipment, systems,
and installations
Proposed Section
23.1300, 23.1310,
23.1305(b) and (c),
and 23.1330(c)
23.1300, 23.1310 and
23.1305(c)
Proposed Title
Airplane level systems
requirements; Flight,
navigation, and powerplant
instruments;
Function and installation;
System power generation,
storage, and distribution
Airplane level systems
requirements; Flight,
navigation, and powerplant
instruments;
Function and installation
23.1320
Electrical and electronic
system lightning protection
23.1300 and 23.1310
Airplane level systems
requirements; Flight,
navigation, and powerplant
instruments
23.1325
High-intensity Radiated
Fields (HIRF) protection
23.1315
Equipment, systems, and
installations
(a)(1)
--
23.1300(a)
Airplane level systems
requirements
(a)(2)
--
23.1300(b)
Airplane level systems
requirements
(b)
--
--
--Deleted--
(c)
--
23.1315(b)
Equipment, systems, and
installations
(b)
--
23.1305(c)
Function and installation
23.1310
Power source capacity
and distribution
23.1311
Electronic display
instrument systems
23.1330
23.1300 and 23.1310
216
System power generation,
storage, and distribution
Airplane level systems
requirements; Flight,
navigation, and powerplant
instruments
Current
Section
Title
Proposed Section
23.1321
Arrangement and
visibility
23.1322
Warning, caution, and
advisory lights
23.1305(b) and (c)
23.1323
Airspeed indicating
system
23.1300, 23.1305,
23.1310, and 1315
(d)
23.1325
(b)(3) and (g)
23.1326
--
Static pressure system
-Pitot heat indication
systems
23.1300 and 23.1310
23.1405
23.1300, 23.1310, and
23.1315
1405
23.1305
23.1327
Magnetic direction
indicator
23.1300, 23.1305 and
23.1310
23.1329
Automatic pilot system
23.1300, 23.1305 and
23.1315
(a)
--
23.1300 and 23.1315
(b)
--
23.700 and 23.1500
217
Proposed Title
Airplane level systems
requirements; Flight,
navigation, and powerplant
instruments
Flight, navigation, and
powerplant instruments
Airplane level systems
requirements;
Function and installation;
Flight, navigation, and
powerplant instruments; and
Equipment, systems, and
installations
Flight in icing conditions
Airplane level systems
requirements;
Flight, navigation, and
powerplant instruments; and
Equipment, systems, and
installations
Flight in icing conditions
Function and installation
Airplane level systems
requirements; Function and
installation;
Flight, navigation, and
powerplant instruments
Airplane level systems
requirements;
Function and installation;
Equipment, systems, and
installations
Airplane level systems
requirements;
Equipment, systems, and
installations
Flight control systems;
Flightcrew interface
Current
Section
Title
Proposed Section
Proposed Title
(c)
--
23.1305
Function and installation
(d)
--
23.700 and 23.1500
(e), (f), (g)
--
23.1300 and 23.1315
(h)
--
23.1305
Function and installation
--
--
--
23.1305(c)
Function and installation
(b)
--
23.1315(b) and
23.1330(b)
(c)
--
23.1310(b)
23.1335
Flight director systems
23.1300, 23.1305,
23.1315, and 23.1500
23.1337
Powerplant instruments
installation
--
--
(a)
--
23.800(g)
Fire protection outside
designated fire zones
--
--
23.930
Fuel systems
(b)
--
23.1305(c) and (d)
Function and installation
--
--
23.1310(a)
Flight, navigation, and
powerplant instruments
23.1331
(a)
Instruments using a
power source
218
Flight control systems;
Flightcrew interface
Airplane level systems
requirements;
Equipment, systems, and
installations
Equipment, systems, and
installations;
System power generation,
storage, and distribution
Flight, navigation, and
powerplant instruments
Airplane level systems;
Function and installation;
Equipment systems and
installations; and
Flightcrew interface
Current
Section
Title
Proposed Section
Proposed Title
--
--
23.1315(b)
Equipment, systems, and
installations
(c)
--
23.1315(b)
Equipment, systems, and
installations
(d)
--
23.1305(c)
Function and installation
--
--
23.1310(a)
Flight, navigation, and
powerplant instruments
23.1300
Airplane level systems
requirements
23.1305
Function and installation
23.1315
Equipment, systems, and
installations
23.1330
System power generation,
storage, and distribution
23.1300
Airplane level systems
requirements
23.1305
Function and installation
23.1315
Equipment, systems, and
installations
23.1330
System power generation,
storage, and distribution
23.1300
Airplane level systems
requirements
23.1305
Function and installation
23.1351
23.1353
23.1357
Electrical Systems General
Storage battery design
and installation
Circuit protective
devices
219
Current
Section
23.1359
Title
Proposed Section
Proposed Title
23.1315
Equipment, systems, and
installations;
23.1330
System power generation,
storage, and distribution
--
--
Electrical system fire
protection
(a)
--
Means Of Compliance
--
(b)
--
805
Flammability in designated
fire zones
(c)
--
800
23.1361
Master switch
arrangement
23.1365
Electrical cables and
equipment
23.1300 and 23.1305
Fire protection outside
designated fire zones
Airplane level systems
requirements; Function and
installation
23.1305
Function and installation
Flammability in designated
fire zones
(b)
--
23.805
(a), (c) thru (f)
--
Means Of Compliance
--
--
--
23.1367
Switches
(a) and (b)
--
23.1305
Function and installation
(c) and (d)
--
23.1500
Flightcrew interface
23.1381
Instrument lights
--
220
--
Current
Section
Title
Proposed Section
(a) and (b)
--
23.1500
Flightcrew interface
(c)
--
23.1335
External and cockpit lighting
23.1383(a),
(b), (c)
Taxi and landing lights
23.1335
External and cockpit lighting
(d)
Taxi and landing lights
23.800
Fire protection outside
designated fire zones
23.1385(a),
(b), (c)
Position light system
installation
23.1335
External and cockpit lighting
(d)
Position light system
installation
23.800
Fire protection outside
designated fire zones
23.1387
Position light system
dihedral angles
23.1335
External and cockpit lighting
23.1389
Position light
distribution and
intensities
23.1335
External and cockpit lighting
23.1391
Minimum intensities in
the horizontal plane of
position lights
23.1335
External and cockpit lighting
23.1393
Minimum intensities in
any vertical plane of
position lights
23.1335
External and cockpit lighting
23.1395
Maximum intensities in
overlapping beams of
position lights
23.1335
External and cockpit lighting
23.1397
Color specifications
23.1335
External and cockpit lighting
23.1399
Riding light
23.1335
External and cockpit lighting
23.1401
Anticollision light
system
--
--
23.1335
External and cockpit lighting
(a), (a)(1)
--
221
Proposed Title
Current
Section
Title
Proposed Section
Proposed Title
(a)(2)
--
Means Of Compliance
--
(b) thru (f)
--
23.1335
External and cockpit lighting
--
--
23.1411
Safety EquipmentGeneral
(a), (b)(1)
--
23.1400
Safety equipment
(b)(2)
--
23.600
Emergency conditions
23.1400
Safety equipment
Safety equipment
23.1415
Ditching equipment
(a), (c), (d)
--
23.1400
(b)
--
Means Of Compliance
23.1416
Pneumatic de-icer boot
system
23.1300
Airplane level systems
requirements.
23.1305
Function and installation.
23.230
Flight in icing conditions
23.1419
Ice protection
23.1405
23.1431
Electronic equipment
23.1435
Hydraulic systems
23.1315
--
(a)(4) and (b)
--
23.1410
(a), (a)(1)
through (3),
(c)
--
Means Of Compliance
23.1437
Accessories for
multiengine airplanes
23.1410
222
--
Performance and flight
characteristics requirements
for flight in icing conditions
Equipment, systems and
installations
-Pressurized system elements
-Pressurized system elements
Current
Section
23.1438
Title
Proposed Section
Proposed Title
--
--
Pressurization and
pneumatic systems
(a), (b)
--
23.1410
(c)
--
Means Of Compliance
--
--
23.1410(e)
23.1441
Oxygen equipment and
supply
--
--
(a)
--
Means Of Compliance
--
(b)
--
23.1315
Equipment, systems and
installation
(c), (d), (e)
--
23.755
Occupant physical
environment
23.1443(a),
(b), (c)
Minimum mass flow of
supplemental oxygen
23.755
Occupant physical
environment
(d)
--
Definition
23.1445
23.1447
Oxygen distribution
system
Equipment standards
for oxygen dispensing
units
23.755
--
(a), (b), (c),
(d), (f)
--
23.755
(e)
--
Means Of Compliance
23.1449
Means for determining
use of oxygen
23.755
23.1450
Chemical oxygen
generators
--
223
Pressurized system elements
-Pressurized system elements
-Occupant physical
environment
-Occupant physical
environment
-Occupant physical
environment
--
Current
Section
Title
Proposed Section
Proposed Title
(a)
--
Means Of Compliance
--
(b)
--
23.1315
Equipment, systems and
installation
(c)
--
23.1505
Instrument markings, control
markings, and placards.
23.1451
Fire protection for
oxygen equipment
23.1315
Equipment, systems and
installation
23.1453
Protection of oxygen
equipment from rupture
23.1315
Equipment, systems and
installation
23.1457
Cockpit voice recorders
23.1457
No Change
23.1459
Flight recorders
--
--
(a)(1)
--
23.1459
Flight data recorders
(a)(2) thru (d)
--
23.1459
No Change
23.755
Occupant physical
environment
23.1461
Equipment containing
high energy rotors
Subpart G - Operating Limitations and Information
23.1501
General
23.1505
Instrument markings, control
markings, and placards.
23.1505
Airspeed limitations
23.1505
Instrument markings, control
markings, and placards.
23.1507
Operating maneuvering
speed
23.1505
Instrument markings, control
markings, and placards.
23.1511
Flap extended speed
23.1505
Instrument markings, control
markings, and placards.
23.1513
Minimum control speed
23.1505
Instrument markings, control
markings, and placards.
224
Current
Section
Title
Proposed Section
Proposed Title
23.1519
Weight and center of
gravity
23.1505
Instrument markings, control
markings, and placards.
23.1521
Powerplant limitations
23.1505
Instrument markings, control
markings, and placards.
23.1522
Auxiliary power unit
limitations
23.1505
Instrument markings, control
markings, and placards.
23.1523
Minimum flight crew
23.1505
Instrument markings, control
markings, and placards.
23.1524
Maximum passenger
seating configuration
23.1505
Instrument markings, control
markings, and placards.
23.1525
Kinds of operation
23.1300
Airplane level system
requirements.
23.1505
Instrument markings, control
markings, and placards
23.1527
Maximum operating
altitude
23.1505
Instrument markings, control
markings, and placards.
23.1529
Instructions for
continued airworthiness
23.1515
Instructions for continued
airworthiness.
23.1541
Marking and Placards General
23.1505
Instrument markings, control
markings, and placards.
23.1543
Instrument marking:
general
23.1505
Instrument markings, control
markings, and placards.
23.1505
23.1545
Airspeed indicator
23.1547
Magnetic direction
indicator
23.1549
Powerplant and
auxiliary power unit
instruments
Instrument markings, control
markings, and placards.
23.1505
Instrument markings, control
markings, and placards.
23.1505
Instrument markings, control
markings, and placards.
225
Current
Section
Title
Proposed Section
Proposed Title
23.1505
23.1551
Instrument markings, control
markings, and placards.
Oil quantity indicator
23.1505
23.1553
Instrument markings, control
markings, and placards.
Fuel quantity indicator
23.1505
23.1555
Control markings
23.1557
Miscellaneous marking
and placards
23.1559
Operating limitations
placard
Instrument markings, control
markings, and placards.
23.1505
Instrument markings, control
markings, and placards.
23.1505
Instrument markings, control
markings, and placards.
23.1505
23.1561
Instrument markings, control
markings, and placards.
Safety equipment
23.1505
Instrument markings, control
markings, and placards.
23.1563
Airspeed placards
23.1567
Flight maneuver
placard
23.1581
Airplane Flight Manual
and Approved Manual
Material - General
23.1510
Airplane flight manual.
23.1583
Operating limitations
23.1510
Airplane flight manual.
23.1585
Operating procedures
23.1510
Airplane flight manual.
23.1587
Performance
information
23.1510
Airplane flight manual.
23.1589
Loading information
23.1510
Airplane flight manual.
23.1505
Appendix A
Simplified Design Load
Criteria
Instrument markings, control
markings, and placards.
Means Of Compliance
226
--
Current
Section
Appendix B
Appendix C
Appendix D
Title
Basic Landing
Conditions
Wheel Spin-Up and
Spring-Back Loads
[Reserved]
Appendix F
Test Procedure
Appendix H
Proposed Title
--
--Deleted--
Means Of Compliance
--
Means Of Compliance
--
--
--Deleted--
Means Of Compliance
--
[Reserved]
Appendix E
Appendix G
Proposed Section
Instructions for
Continued
Airworthiness
Installation of An
Automatic Power
Reserve (APR) System
Appendix A
Instructions for Continued
Airworthiness
Means Of Compliance
--
Appendix I
Seaplane Loads
Means Of Compliance
--
Appendix J
HIRF Environments
and Equipment HIRF
Test Levels
Means Of Compliance
--
Appendix 2 to the Preamble—Abbreviations and Acronyms Frequently Used In This Document
AD
Airworthiness Directive
AFM
Airplane Flight Manual
ARC
Aviation Rulemaking Committee
ASTM
ASTM International
CAA
Civil Aviation Authority
CAR
Civil Aviation Regulations
Cf
Confer (to identify a source or a usage citation for a word or phrase)
CPS
Certification Process Study
CS
Certification Specification
CS-VLA
Certification Specification-Very Light Aeroplanes
227
EASA
European Aviation Safety Agency
ELOS
Equivalent Level of Safety
FR
Federal Register
GA
General Aviation
HIRF
High-Intensity Radiated Field
IFR
Instrument Flight Rules
KCAS
Knots Calibrated Airspeeds
LOC
Loss of Control
NPRM
Notice of Proposed Rulemaking
NTSB
National Transportation Safety Board
OMB
Office of Management and Budget
SAE
SAE International
SLD
Supercooled Large Droplet
TCDS
Type Certificate Data Sheet
VA
Design Maneuvering Speed
VC
Design Cruising Speed
VD
Design Dive Speed
VMC
Minimum Control Speed
VMO/MMO
Maximum Operating Limit Speed
VFR
Visual Flight Rules
VSO
Stalling speed or the minimum steady flight speed in the landing
configuration
228
List of Subjects
14 CFR Part 21
Aircraft, Aviation safety, Recording and recordkeeping requirements.
14 CFR Part 23
Aircraft, Aviation Safety, Signs and symbols.
14 CFR Part 35
Aircraft, Aviation safety
14 CFR Part 43
Aircraft, Aviation safety, Reporting and recordkeeping requirements.
14 CFR Part 91
Air traffic control, Aircraft, Airmen, Airports, Aviation safety, Reporting and recordkeeping
requirements.
14 CFR Part 121
Aircraft, Airmen, Aviation safety, Reporting and recordkeeping requirements
14 CFR Part 135
Aircraft, Airmen, Aviation safety, Reporting and recordkeeping requirements
The Proposed Amendment
In consideration of the foregoing, the Federal Aviation Administration proposes to amend chapter I
of title 14, Code of Federal Regulations as follows:
PART 21—CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES
1. The authority citation for part 21 is revised to read as follows:
Authority: 42 U.S.C. 7572; 49 U.S.C. 106(f), 106(g), 40105, 40113, 44701-44702, 44704, 44707,
44709, 44711, 44713, 44715, 45303.
229
2. In § 21.9, revise paragraphs (a)(5), (a)(6), (b), and (c) introductory text, and add paragraph (a)(7)
to read as follows:
§ 21.9 Replacement and modification articles.
(a) * * *
(5) Produced by an owner or operator for maintaining or altering that owner or operator's product;
(6) Fabricated by an appropriately rated certificate holder with a quality system, and consumed in
the repair or alteration of a product or article in accordance with part 43 of this chapter; or
(7) Produced in any other manner approved by the FAA.
(b) Except as provided in paragraphs (a)(1), (a)(2) and (a)(7) of this section, a person who produces
a replacement or modification article for sale may not represent that part as suitable for installation on a
type-certificated product.
(c) Except as provided in paragraphs (a)(1), (a)(2) and (a)(7) of this section, a person may not
sell or represent an article as suitable for installation on an aircraft type-certificated under § 21.25(a)(2)
or § 21.27 unless that article—
*
*
*
*
*
3. In § 21.17, revise paragraph (a) introductory text to read as follows:
§ 21.17 Designation of applicable regulations.
(a) Except as provided in §§ 25.2, 27.2, 29.2, and in parts 26, 34, and 36 of this subchapter, an
applicant for a type certificate must show that the aircraft, aircraft engine, or propeller concerned
meets—
*
*
*
*
*
4. In § 21.24, revise paragraph (a)(1)(i) to read as follows:
230
§ 21.24 Issuance of type certificate: primary category aircraft.
(a) * * *
(1) * * *
(i) Is unpowered; is an airplane powered by a single, naturally aspirated engine with a 61-knot or
less Vso stall speed as defined in § 23.49 of this chapter, at amendment 23-62, effective on Jan 31, 2012;
or is a rotorcraft with a 6-pound per square foot main rotor disc loading limitation, under sea level
standard day conditions;
*
*
*
*
*
5. In § 21.35, revise paragraph (b)(2) to read as follows:
§ 21.35 Flight tests
*
*
*
*
*
(b) * * *
(2) For aircraft to be certificated under this subchapter, except gliders, and except for low-speed
airplanes, as defined in part 23 of this chapter, of 6,000 pounds or less maximum weight that are to be
certificated under part 23 of this chapter, to determine whether there is reasonable assurance that the
aircraft, its components, and its equipment are reliable and function properly.
*
*
*
*
*
6. In § 21.50, revise paragraph (b) to read as follows:
§ 21.50 Instructions for continued airworthiness and manufacturer's maintenance manuals
having airworthiness limitations sections.
*
*
*
*
*
(b) The holder of a design approval, including either a type certificate or supplemental type
certificate for an aircraft, aircraft engine, or propeller for which application was made after January 28,
231
1981, must furnish at least one set of complete Instructions for Continued Airworthiness to the owner of
each type aircraft, aircraft engine, or propeller upon its delivery, or upon issuance of the first standard
airworthiness certificate for the affected aircraft, whichever occurs later. The Instructions for Continued
Airworthiness must be prepared in accordance with §§ 23.1515, 25.1529, 25.1729, 27.1529, 29.1529,
31.82, 33.4, 35.4, or part 26 of this subchapter, or as specified in the applicable airworthiness criteria for
special classes of aircraft defined in § 21.17(b), as applicable. If the holder of a design approval chooses
to designate parts as commercial, it must include in the Instructions for Continued Airworthiness a list of
commercial parts submitted in accordance with the provisions of paragraph (c) of this section.
Thereafter, the holder of a design approval must make those instructions available to any other person
required by this chapter to comply with any of the terms of those instructions. In addition, changes to the
Instructions for Continued Airworthiness shall be made available to any person required by this chapter
to comply with any of those instructions.
*
*
*
*
*
7. In § 21.101 revise paragraphs (b) introductory text, and (c) to read as follows:
§ 21.101 Designation of applicable regulations.
*
*
*
*
*
(b) Except as provided in paragraph (g) of this section, if paragraphs (b)(1), (2), or (3) of this
section apply, an applicant may show that the change and areas affected by the change comply with an
earlier amendment of a regulation required by paragraph (a) of this section, and of any other regulation
the FAA finds is directly related. However, the earlier amended regulation may not precede either the
corresponding regulation incorporated by reference in the type certificate, or any regulation in §§ 25.2,
27.2, or § 29.2 of this chapter that is related to the change. The applicant may show compliance with an
earlier amendment of a regulation for any of the following:
232
*
*
*
*
*
(c) An applicant for a change to an aircraft (other than a rotorcraft) of 6,000 pounds or less
maximum weight, to a non-turbine rotorcraft of 3,000 pounds or less maximum weight, to a simple, to a
level 1 low speed, or to a level 2 low speed airplane may show that the change and areas affected by the
change comply with the regulations incorporated by reference in the type certificate. However, if the
FAA finds that the change is significant in an area, the FAA may designate compliance with an
amendment to the regulation incorporated by reference in the type certificate that applies to the change
and any regulation that the FAA finds is directly related, unless the FAA also finds that compliance with
that amendment or regulation would not contribute materially to the level of safety of the product or
would be impractical.
*
*
*
*
*
8. Revise part 23 to read as follows:
PART 23—AIRWORTHINESS STANDARDS: NORMAL CATEGORY AIRPLANES
Sec.
Subpart A—General
23.1 Applicability and definitions.
23.5 Certification of normal category airplanes.
23.10 Accepted means of compliance.
Subpart B—Flight
PERFORMANCE
23.100 Weight and center of gravity.
23.105 Performance data.
23.110 Stall speed.
23.115 Takeoff performance.
23.120 Climb requirements.
23.125 Climb information.
23.130 Landing.
FLIGHT CHARACTERISTICS
23.200 Controllability.
23.205 Trim.
233
23.210 Stability.
23.215 Stall characteristics, stall warning, and spins.
23.220 Ground and water handling characteristics.
23.225 Vibration, buffeting, and high-speed characteristics.
23.230 Performance and flight characteristics requirements for flight in icing conditions.
Subpart C—Structures
23.300 Structural design envelope.
23.305 Interaction of systems and structures.
STRUCTURAL LOADS
23.310 Structural design loads.
23.315 Flight load conditions.
23.320 Ground and water load conditions.
23.325 Component loading conditions.
23.330 Limit and ultimate loads.
STRUCTURAL PERFORMANCE
23.400 Structural strength.
23.405 Structural durability.
23.410 Aeroelasticity.
DESIGN
23.500 Structural design.
23.505 Protection of structure.
23.510 Materials and processes.
23.515 Special factors of safety.
STRUCTURAL OCCUPANT PROTECTION.
23.600 Emergency conditions.
Subpart D—Design and Construction
23.700 Flight control systems.
23.705 Landing gear systems.
23.710 Buoyancy for seaplanes and amphibians.
OCCUPANT SYSTEM DESIGN PROTECTION
23.750 Means of egress and emergency exits.
23.755 Occupant physical environment.
FIRE AND HIGH ENERGY PROTECTION
23.800 Fire protection outside designated fire zones.
23.805 Fire protection in designated fire zones.
23.810 Lightning protection of structure.
Subpart E—Powerplant
23.900 Powerplant installation.
23.905 Propeller installation.
23.910 Powerplant installation hazard assessment.
23.915 Automatic power control systems.
23.920 Reversing systems.
23.925 Powerplant operational characteristics.
23.930 Fuel system.
23.935 Powerplant induction and exhaust systems.
23.940 Powerplant ice protection.
234
23.1000 Powerplant fire protection.
Subpart F—Equipment
23.1300 Airplane level systems requirements.
23.1305 Function and installation.
23.1310 Flight, navigation, and powerplant instruments.
23.1315 Equipment, systems, and installations.
23.1320 Electrical and electronic system lightning protection.
23.1325 High-intensity Radiated Fields (HIRF) Protection.
23.1330 System power generation, storage, and distribution.
23.1335 External and cockpit lighting.
23.1400 Safety equipment.
23.1405 Flight in icing conditions.
23.1410 Pressurized system elements.
23.1457 Cockpit voice recorders.
23.1459 Flight data recorders.
Subpart G—Flightcrew Interface and Other Information
23.1500 Flightcrew interface.
23.1505 Instrument and control markings and placards.
23.1510 Airplane flight manual.
23.1515 Instructions for continued airworthiness.
Appendices
APPENDIX A TO PART 23—INSTRUCTIONS FOR CONTINUED AIRWORTHINESS
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704, Pub. L. 113-53, 127 Stat. 584 (49
U.S.C. 44704) note.
Subpart A—General
§ 23.1 Applicability and definitions.
(a) This part prescribes airworthiness standards for the issuance of type certificates, and changes to
those certificates, for airplanes in the normal category.
(b) For the purposes of this part, the following definitions apply:
(1) Continued safe flight and landing means an airplane is capable of continued controlled flight
and landing, possibly using emergency procedures, without requiring exceptional pilot skill or strength.
Upon landing, some airplane damage may occur as a result of a failure condition.
235
(2) Designated fire zone means a zone where catastrophic consequences from fire in that zone must
be mitigated by containing the fire in that zone.
(3) Empty weight means the weight of the airplane with fixed ballast, unusable fuel, full operating
fluids, and other fluids required for normal operation of airplane systems.
§ 23.5 Certification of normal category airplanes.
(a) Certification in the normal category applies to airplanes with a passenger-seating configuration
of 19 or less and a maximum certificated takeoff weight of 19,000 pounds or less.
(b) Airplane certification levels are:
(1) Level 1 – for airplanes with a maximum seating configuration of 0 to 1 passengers.
(2) Level 2 – for airplanes with a maximum seating configuration of 2 to 6 passengers.
(3) Level 3 – for airplanes with a maximum seating configuration of 7 to 9 passengers.
(4) Level 4 – for airplanes with a maximum seating configuration of 10 to 19 passengers.
(c) Airplane performance levels are:
(1) Low speed – for airplanes with a VC or VMO ≤ 250 Knots Calibrated Airspeed (KCAS) (and
MMO ≤ 0.6).
(2) High speed – for airplanes with a VC or VMO > 250 KCAS (or MMO > 0.6).
(d) Simple – Simple is defined as a level 1 airplane with a VC or VMO ≤ 250 KCAS (and MMO ≤
0.6), a VSO ≤ 45 KCAS and approved only for VFR operations.
(e) Airplanes not certified for aerobatics may be used to perform any maneuver incident to normal
flying, including—
(1) Stalls (except whip stalls); and
(2) Lazy eights, chandelles, and steep turns, in which the angle of bank is not more than 60 degrees.
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(f) Airplanes certified for aerobatics may be used to perform maneuvers without limitations, other
than those limitations necessary to avoid damage or injury.
§ 23.10 Accepted means of compliance.
(a) An applicant must show the FAA how it will demonstrate compliance with this part using a
means of compliance, which may include consensus standards, accepted by the Administrator.
(b) A person requesting acceptance of a means of compliance must provide the means of
compliance to the FAA in a form and manner specified by the Administrator.
Subpart B—Flight
PERFORMANCE
§ 23.100 Weight and center of gravity.
(a) The applicant must determine weights and centers of gravity that provide limits for the safe
operation of the airplane.
(b) The applicant must show compliance with each requirement of this subpart at each combination
of weight and center of gravity within the airplane’s range of loading conditions using tolerances
acceptable to the Administrator.
(c) The condition of the airplane at the time of determining its empty weight and center of gravity
must be well defined and easily repeatable.
§ 23.105 Performance data.
(a) Unless otherwise prescribed, an airplane must meet the performance requirements of this
subpart in—
(1) Still air and standard atmospheric conditions at sea level for all airplanes; and
(2) Ambient atmospheric conditions within the operating envelope for—
(i) Level 1 high-speed and level 2 high-speed airplanes; and
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(ii) Levels 3 and 4 airplanes.
(b) Unless otherwise prescribed, the applicant must develop the performance data required by this
subpart for the following conditions:
(1) Airport altitudes from sea level to 10,000 feet (3,048 meters); and
(2) Temperatures from standard to 30° Celsius above standard or the maximum ambient
atmospheric temperature at which compliance with propulsion cooling requirements in climb is shown,
if lower.
(c) The procedures used for determining takeoff and landing distances must be executable
consistently by pilots of average skill in atmospheric conditions expected to be encountered in service.
(d) Performance data determined in accordance with paragraph (b) of this section must account for
losses due to atmospheric conditions, cooling needs, and other demands on power sources.
§ 23.110 Stall speed.
The applicant must determine the airplane stall speed or the minimum steady flight speed for each
flight configuration used in normal operations, including takeoff, climb, cruise, descent, approach, and
landing. Each determination must account for the most adverse conditions for each flight configuration
with power set at idle or zero thrust.
§ 23.115 Takeoff performance.
(a) The applicant must determine airplane takeoff performance accounting for—
(1) Stall speed safety margins;
(2) Minimum control speeds; and
(3) Climb gradients.
(b) For all airplanes, takeoff performance includes the determination of ground roll and initial climb
distance to 50 feet (15 meters) above the takeoff surface.
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(c) For levels 1, 2, and 3 high-speed multiengine airplanes, multiengine airplanes with a maximum
takeoff weight greater than 12,500 pounds and level 4 multiengine airplanes, takeoff performance
includes a determination the following distances after a sudden critical loss of thrust:
(1) Accelerate-stop;
(2) Ground roll and initial climb to 50 feet (15 meters) above the takeoff surface; and
(3) Net takeoff flight path.
§ 23.120 Climb requirements.
The applicant must demonstrate the following minimum climb performance out of ground effect:
(a) With all engines operating and in the initial climb configuration—
(1) For levels 1 and 2 low speed airplanes, a climb gradient at sea level of 8.3 percent for
landplanes and 6.7 percent for seaplanes and amphibians; and
(2) For levels 1 and 2 high-speed airplanes and all level 3 airplanes, a climb gradient at takeoff of 4
percent.
(b) After a critical loss of thrust on multiengine airplanes—
(1) For levels 1and 2 low-speed airplanes that do not meet single engine crashworthiness
requirements, a 1.5 percent climb gradient at a pressure altitude of 5,000 feet (1,524 meters) in the cruise
configuration;
(2) For levels 1 and 2 high-speed airplanes, and level 3 low-speed airplanes, a 1 percent climb
gradient at 400 feet (122 meters) above the takeoff surface with the landing gear retracted and flaps in
the takeoff configuration;
(3) For level 3 high-speed airplanes and all level 4 airplanes, a 2 percent climb gradient at 400 feet
(122 meters) above the takeoff surface with the landing gear retracted and flaps in the approach
configuration;
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(4) At sea level for level 1 and level 2 low-speed airplanes; and
(5) At the landing surface for all other airplanes.
(c) For a balked landing, a climb gradient of 3 percent with—
(1) Takeoff power on each engine;
(2) Landing gear extended; and
(3) Flaps in the landing configuration.
§ 23.125 Climb information.
(a) The applicant must determine climb performance—
(1) For all single engine airplanes;
(2) For level 3 multiengine airplanes, following a critical loss of thrust on takeoff in the initial
climb configuration; and
(3) For all multiengine airplanes, during the enroute phase of flight with all engines operating and
after a critical loss of thrust in the cruise configuration.
(b) For single engine airplanes, the applicant must determine the glide performance of the airplane
after a complete loss of thrust.
§ 23.130 Landing.
The applicant must determine the following, for standard temperatures at each weight and altitude
within the operational limits for landing:
(a) The distance, starting from a height of 50 feet (15 meters) above the landing surface, required to
land and come to a stop, or for water operations, reach a speed of 3 knots.
(b) The approach and landing speeds, configurations, and procedures, which allow a pilot of
average skill to meet the landing distance consistently and without causing damage or injury.
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FLIGHT CHARACTERISTICS
§ 23.200 Controllability.
(a) The airplane must be controllable and maneuverable, without requiring exceptional piloting
skill, alertness, or strength, within the operating envelope—
(1) At all loading conditions for which certification is requested;
(2) During low-speed operations, including stalls;
(3) With any probable flight control or propulsion system failure; and
(4) During configuration changes.
(b) The airplane must be able to complete a landing without causing damage or serious injury, in
the landing configuration at a speed of VREF minus 5 knots using the approach gradient equal to the
steepest used in the landing distance determination.
(c) For levels 1 and 2 multiengine airplanes that cannot climb after a critical loss of thrust, VMC
must not exceed VS1 or VS0 for all practical weights and configurations within the operating envelope of
the airplane.
(d) If the applicant requests certification of an airplane for aerobatics, the applicant must
demonstrate those aerobatic maneuvers for which certification is requested and determine entry speeds.
§ 23.205 Trim.
(a) The airplane must maintain longitudinal, lateral, and directional trim under the following
conditions:
(1) For levels 1, 2, and 3 airplanes, in cruise, without further force upon, or movement of, the
primary flight controls or corresponding trim controls by the pilot, or the flight control system.
(2) For level 4 airplanes in normal operations, without further force upon, or movement of, the
primary flight controls or corresponding trim controls by the pilot, or the flight control system.
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(b) The airplane must maintain longitudinal trim under the following conditions:
(1) Climb.
(2) Level flight.
(3) Descent.
(4) Approach.
(c) Residual forces must not fatigue or distract the pilot during likely emergency operations,
including a critical loss of thrust on multiengine airplanes.
§ 23.210 Stability.
(a) Airplanes not certified for aerobatics must—
(1) Have static longitudinal, lateral, and directional stability in normal operations;
(2) Have dynamic short period and combined lateral-directional stability in normal operations; and
(3) Provide stable control force feedback throughout the operating envelope.
(b) No airplane may exhibit any divergent longitudinal stability characteristic so unstable as to
increase the pilot’s workload or otherwise endanger the airplane and its occupants.
§ 23.215 Stall characteristics, stall warning, and spins.
(a) The airplane must have controllable stall characteristics in straight flight, turning flight, and
accelerated turning flight with a clear and distinctive stall warning that provides sufficient margin to
prevent inadvertent stalling.
(b) Levels 1 and 2 airplanes and level 3 single-engine airplanes, not certified for aerobatics, must
not have a tendency to inadvertently depart controlled flight.
(c) Airplanes certified for aerobatics must have controllable stall characteristics and the ability to
recover within one and one-half additional turns after initiation of the first control action from any point
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in a spin, not exceeding six turns or any greater number of turns for which certification is requested,
while remaining within the operating limitations of the airplane.
(d) Spin characteristics in airplanes certified for aerobatics must not result in unrecoverable spins—
(1) With any use of the flight or engine power controls; or
(2) Due to pilot disorientation or incapacitation.
§ 23.220 Ground and water handling characteristics.
(a) For airplanes intended for operation on land or water, the airplane must have controllable
longitudinal and directional handling characteristics during taxi, takeoff, and landing operations.
(b) For airplanes intended for operation on water, the following must be established and included in
the Airplane Flight Manual (AFM):
(1) The maximum wave height at which the aircraft demonstrates compliance to § 23.220(a). This
wave height does not constitute an operating limitation.
(2) Any necessary water handling procedures.
§ 23.225 Vibration, buffeting, and high-speed characteristics.
(a) Vibration and buffeting, for operations up to VD/MD, must not interfere with the control of the
airplane or cause fatigue to the flightcrew. Stall warning buffet within these limits is allowable.
(b) For high-speed airplanes and all airplanes with a maximum operating altitude greater than
25,000 feet (7,620 meters) pressure altitude, there must be no perceptible buffeting in cruise
configuration at 1g and at any speed up to VMO/MMO, except stall buffeting.
(c) For high-speed airplanes, the applicant must determine the positive maneuvering load factors at
which the onset of perceptible buffet occurs in the cruise configuration within the operational envelope.
Likely inadvertent excursions beyond this boundary must not result in structural damage.
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(d) High-speed airplanes must have recovery characteristics that do not result in structural damage
or loss of control, beginning at any likely speed up to VMO/MMO, following—
(1) An inadvertent speed increase; and
(2) A high-speed trim upset.
§ 23.230 Performance and flight characteristics requirements for flight in icing conditions.
(a) If an applicant requests certification for flight in icing conditions as specified in part 1 of
appendix C to part 25 of this chapter and any additional atmospheric icing conditions for which an
applicant requests certification, the applicant must demonstrate the following:
(1) Compliance with each requirement of this subpart, except those applicable to spins and any that
must be demonstrated at speeds in excess of—
(i) 250 knots CAS;
(ii) VMO or MMO; or
(iii) A speed at which the applicant demonstrates the airframe will be free of ice accretion.
(2) The stall warning for flight in icing conditions and non-icing conditions is the same.
(b) If an applicant requests certification for flight in icing conditions, the applicant must provide a
means to detect any icing conditions for which certification is not requested and demonstrate the
aircraft’s ability to avoid or exit those conditions.
(c) The applicant must develop an operating limitation to prohibit intentional flight, including
takeoff and landing, into icing conditions for which the airplane is not certified to operate.
Subpart C—Structures
§ 23.300 Structural design envelope.
The applicant must determine the structural design envelope, which describes the range and limits
of airplane design and operational parameters for which the applicant will show compliance with the
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requirements of this subpart. The applicant must account for all airplane design and operational
parameters that affect structural loads, strength, durability, and aeroelasticity, including:
(a) Structural design airspeeds and Mach numbers, including—
(1) The design maneuvering airspeed, VA, which may be no less than the airspeed at which the
airplane will stall at the maximum design maneuvering load factor;
(2) The design cruising airspeed, VC or MC, which may be no less than the maximum speed
expected in normal operations;
(3) The design dive airspeed, VD or MD, which is the airspeed that will not be exceeded by
inadvertent airspeed increases when operating at VC or MC;
(4) Any other design airspeed limitations required for the operation of high lift devices, landing
gear, and other equipment or devices; and
(5) For level 4 airplanes, a rough air penetration speed, VB.
(b) Design maneuvering load factors not less than those, which service history shows, may occur
within the structural design envelope.
(c) Inertial properties including weight, center of gravity, and mass moments of inertia, accounting
for—
(1) All weights from the airplane empty weight to the maximum weight; and
(2) The weight and distribution of occupants, payload, and fuel.
(d) Range of motion for control surfaces, high lift devices, or other moveable surfaces, including
tolerances.
(e) All altitudes up to the maximum altitude.
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§ 23.305 Interaction of systems and structures.
For airplanes equipped with systems that affect structural performance, either directly or as a result
of failure or malfunction, the applicant must account for the influence and failure conditions of these
systems when showing compliance with the requirements of this subpart.
STRUCTURAL LOADS
§ 23.310 Structural design loads.
The applicant must:
(a) Determine structural design loads resulting from any externally or internally applied pressure,
force, or moment which may occur in flight, ground and water operations, ground and water handling,
and while the airplane is parked or moored.
(b) Determine the loads required by paragraph (a) of this section at all critical combinations of
parameters, on and within the boundaries of the structural design envelope.
(c) The magnitude and distribution of these loads must be based on physical principles and may be
no less than service history shows will occur within the structural design envelope.
§ 23.315 Flight load conditions.
The applicant must determine the structural design loads resulting from the following flight
conditions:
(a) Vertical and horizontal atmospheric gusts where the magnitude and gradient of these gusts are
based on measured gust statistics.
(b) Symmetric and asymmetric maneuvers.
(c) For canted lifting surfaces, vertical and horizontal loads acting simultaneously resulting from
gust and maneuver conditions.
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(d) For multiengine airplanes, failure of the powerplant unit which results in the most severe
structural loads.
§ 23.320 Ground and water load conditions.
The applicant must determine the structural design loads resulting from the following ground and
water operations:
(a) For airplanes intended for operation on land—taxi, takeoff, landing, and ground handling
conditions occurring in normal and adverse attitudes and configurations.
(b) For airplanes intended for operation on water—taxi, takeoff, landing, and water handling
conditions occurring in normal and adverse attitudes and configurations in the most severe sea
conditions expected in operation.
(c) Jacking and towing conditions.
§ 23.325 Component loading conditions.
The applicant must determine the structural design loads acting on:
(a) Each engine mount and its supporting structure resulting from engine operation combined with
gusts and maneuvers.
(b) Each flight control and high lift surface, their associated system and supporting structure
resulting from—
(1) The inertia of each surface and mass balance attachment;
(2) Gusts and maneuvers;
(3) Pilot or automated system inputs;
(4) System induced conditions, including jamming and friction; and
(5) Ground operations, including downwind taxi and ground gusts.
(c) A pressurized cabin resulting from the pressurization differential—
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(1) From zero up to the maximum relief valve setting combined with gust and maneuver loads;
(2) From zero up to the maximum relief valve setting combined with ground and water loads if the
airplane may land with the cabin pressurized; and
(3) At the maximum relief valve setting multiplied by 1.33, omitting all other loads.
§ 23.330 Limit and ultimate loads.
Unless special or other factors of safety are necessary to meet the requirements of this subpart, the
applicant must determine—
(a) The limit loads, which are equal to the structural design loads; and
(b) The ultimate loads, which are equal to the limit loads multiplied by a 1.5 factor of safety.
STRUCTURAL PERFORMANCE
§ 23.400 Structural strength.
The applicant must demonstrate that the structure will support:
(a) Limit loads without—
(1) Interference with the operation of the airplane; and
(2) Detrimental permanent deformation.
(b) Ultimate loads.
§ 23.405 Structural durability.
(a) The applicant must develop and implement procedures to prevent structural failures due to
foreseeable causes of strength degradation, which could result in serious or fatal injuries, loss of the
airplane, or extended periods of operation with reduced safety margins. The Instructions for Continued
Airworthiness must include procedures developed under this section.
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(b) If a pressurized cabin has two or more compartments separated by bulkheads or a floor, the
applicant must design the structure for a sudden release of pressure in any compartment that has a door
or window, considering failure of the largest door or window opening in the compartment.
(c) For airplanes with maximum operating altitude greater than 41,000 feet, the procedures
developed for compliance to paragraph (a) of this section must be capable of detecting damage to the
pressurized cabin structure before the damage could result in rapid decompression that would result in
serious or fatal injuries.
(d) The airplane must be capable of continued safe flight and landing with structural damage caused
by high-energy fragments from an uncontained engine or rotating machinery failure.
§ 23.410 Aeroelasticity.
(a) The airplane must be free from flutter, control reversal, and divergence—
(1) At all speeds within and sufficiently beyond the structural design envelope;
(2) For any configuration and condition of operation;
(3) Accounting for critical degrees of freedom; and
(4) Accounting for any critical failures or malfunctions.
(b) The applicant must establish and account for tolerances for all quantities that affect flutter.
DESIGN
§ 23.500 Structural design.
(a) The applicant must design each part, article, and assembly for the expected operating conditions
of the airplane.
(b) Design data must adequately define the part, article, or assembly configuration, its design
features, and any materials and processes used.
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(c) The applicant must determine the suitability of each design detail and part having an important
bearing on safety in operations.
(d) The control system must be free from jamming, excessive friction, and excessive deflection
when—
(1) The control system and its supporting structure are subjected to loads corresponding to the limit
airloads;
(2) The primary controls are subjected to the lesser of the limit airloads or limit pilot forces; and
(3) The secondary controls are subjected to loads not less than those corresponding to maximum
pilot effort.
§ 23.505 Protection of structure.
(a) The applicant must protect each part of the airplane, including small parts such as fasteners,
against deterioration or loss of strength due to any cause likely to occur in the expected operational
environment.
(b) Each part of the airplane must have adequate provisions for ventilation and drainage.
(c) For each part that requires maintenance, preventive maintenance, or servicing, the applicant
must incorporate a means into the aircraft design to allow such actions to be accomplished.
§ 23.510 Materials and processes.
(a) The applicant must determine the suitability and durability of materials used for parts, articles,
and assemblies, the failure of which could prevent continued safe flight and landing. The applicant must
account for the effects of likely environmental conditions expected in service.
(b) The methods and processes of fabrication and assembly used must produce consistently sound
structures. If a fabrication process requires close control to reach this objective, the applicant must
perform the process under an approved process specification.
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(c) Except as provided in paragraphs (f) and (g) of this section, the applicant must select design
values that ensure material strength with probabilities that account for the criticality of the structural
element. Design values must account for the probability of structural failure due to material variability.
(d) If material strength properties are required, a determination of those properties must be based on
sufficient tests of material meeting specifications to establish design values on a statistical basis.
(e) If thermal effects are significant on an essential component or structure under normal operating
conditions, the applicant must determine those effects on allowable stresses used for design.
(f) Design values, greater than the minimums specified by this section, may be used, where only
guaranteed minimum values are normally allowed, if a specimen of each individual item is tested before
use to determine that the actual strength properties of that particular item will equal or exceed those used
in the design.
(g) An applicant may use other material design values if approved by the Administrator.
§ 23.515 Special factors of safety.
(a) The applicant must determine a special factor of safety for any critical design value that is—
(1) Uncertain;
(2) Used for a part, article, or assembly that is likely to deteriorate in service before normal
replacement; or
(3) Subject to appreciable variability because of uncertainties in manufacturing processes or
inspection methods.
(b) The applicant must determine a special factor of safety using quality controls and specifications
that account for each—
(1) Structural application;
(2) Inspection method;
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(3) Structural test requirement;
(4) Sampling percentage; and
(5) Process and material control.
(c) The applicant must apply any special factor of safety in the design for each part of the structure
by multiplying each limit load and ultimate load by the special factor of safety.
STRUCTURAL OCCUPANT PROTECTION
§ 23.600 Emergency conditions.
(a) The airplane, even when damaged in an emergency landing, must protect each occupant against
injury that would preclude egress when—
(1) Properly using safety equipment and features provided for in the design;
(2) The occupant experiences ultimate static inertia loads likely to occur in an emergency landing;
and
(3) Items of mass, including engines or auxiliary power units (APUs), within or aft of the cabin,
that could injure an occupant, experience ultimate static inertia loads likely to occur in an emergency
landing.
(b) The emergency landing conditions specified in paragraph (a) of this section, must—
(1) Include dynamic conditions that are likely to occur with an impact at stall speed, accounting for
variations in aircraft mass, flight path angle, flight pitch angle, yaw, and airplane configuration,
including likely failure conditions at impact; and
(2) Not exceed established human injury criteria for human tolerance due to restraint or contact
with objects in the airplane.
(c) The airplane must have seating and restraints for all occupants. The airplane seating, restraints,
and cabin interior must account for likely flight and emergency landing conditions.
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(d) Each occupant restraint system must consist of a seat, a method to restrain the occupant’s pelvis
and torso, and a single action restraint release. For all flight and ground loads during normal operation
and any emergency landing conditions, the restraint system must perform its intended function and not
create a hazard that could cause a secondary injury to an occupant. The restraint system must not prevent
occupant egress or interfere with the operation of the airplane when not in use.
(e) Each baggage and cargo compartment must—
(1) Be designed for its maximum weight of contents and for the critical load distributions at the
maximum load factors corresponding to the flight and ground load conditions determined under this
part;
(2) Have a means to prevent the contents of the compartment from becoming a hazard by impacting
occupants or shifting; and
(3) Protect any controls, wiring, lines, equipment, or accessories whose damage or failure would
affect operations.
Subpart D—Design and Construction
§ 23.700 Flight control systems.
(a) The applicant must design airplane flight control systems to:
(1) Prevent major, hazardous, and catastrophic hazards, including—
(i) Failure;
(ii) Operational hazards;
(iii) Flutter;
(iv) Asymmetry; and
(v) Misconfiguration.
(2) Operate easily, smoothly, and positively enough to allow normal operation.
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(b) The applicant must design trim systems to:
(1) Prevent inadvertent, incorrect, or abrupt trim operation.
(2) Provide a means to indicate—
(i) The direction of trim control movement relative to airplane motion;
(ii) The trim position with respect to the trim range;
(iii) The neutral position for lateral and directional trim; and
(iv) For all airplanes, except simple airplanes, the range for takeoff for all applicant requested
center of gravity ranges and configurations.
(3) Except for simple airplanes, provide control for continued safe flight and landing when any one
connecting or transmitting element in the primary flight control system fails.
(4) Limit the range of travel to allow safe flight and landing, if an adjustable stabilizer is used.
(c) For an airplane equipped with an artificial stall barrier system, the system must—
(1) Prevent uncommanded control or thrust action; and
(2) Provide for a preflight check.
(d) For level 3 high-speed and all level 4 airplanes, an applicant must install a takeoff warning
system on the airplane unless the applicant demonstrates the airplane, for each configuration, can takeoff
at the limits of the trim and flap ranges.
§ 23.705 Landing gear systems.
(a) For airplanes with retractable landing gear:
(1) The landing gear and retracting mechanism, including the wheel well doors, must be able to
withstand operational and flight loads.
(2) The airplane must have—
(i) A positive means to keep the landing gear extended;
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(ii) A secondary means of extension for landing gear that cannot be extended using the primary
means;
(iii) A means to inform the pilot that each landing gear is secured in the extended and retracted
positions; and
(iv) Except for airplanes intended for operation on water, a warning to the pilot if the thrust and
configuration is selected for landing and the landing gear is not fully extended and locked.
(3) If the landing gear bay is used as the location for equipment other than the landing gear, that
equipment must be designed and installed to avoid damage from tire burst and from items that may enter
the landing gear bay.
(b) The design of each landing gear wheel, tire, and ski must account for critical loads, including
those experienced during landing and rejected takeoff.
(c) A reliable means of stopping the airplane must provide kinetic energy absorption within the
airplane’s design specifications for landing.
(d) For levels 3 and 4 multiengine airplanes, the braking system must provide kinetic energy
absorption within the airplane’s design specifications for rejected takeoff.
§ 23.710 Buoyancy for seaplanes and amphibians.
Airplanes intended for operations on water, must—
(a) Provide buoyancy of 80 percent in excess of the buoyancy required to support the maximum
weight of the airplane in fresh water; and
(b) Have sufficient watertight compartments so the airplane will stay afloat at rest in calm water
without capsizing if any two compartments of any main float or hull are flooded.
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OCCUPANT SYSTEM DESIGN PROTECTION
§ 23.750 Means of egress and emergency exits.
(a) The airplane cabin exit design must provide for evacuation of the airplane within 90 seconds in
conditions likely to occur following an emergency landing. Likely conditions exclude ditching for all
but levels 3 and 4 multiengine airplanes.
(b) Each exit must have a means to be opened from both inside and outside the airplane, when the
internal locking mechanism is in the locked and unlocked position. The means of opening must be
simple, obvious, and marked inside and outside the airplane.
(c) Airplane evacuation paths must protect occupants from serious injury from the propulsion
system.
(d) Each exit must not be obstructed by a seat or seat back, unless the seat or seat back can be easily
moved in one action to clear the exit.
(e) Airplanes certified for aerobatics must have a means to egress the airplane in flight.
(f) Doors, canopies, and exits must be protected from opening inadvertently in flight.
§ 23.755 Occupant physical environment.
(a) The applicant must design the airplane to—
(1) Allow clear communication between the flightcrew and passengers;
(2) Provide a clear, sufficiently undistorted external view to enable the flightcrew to perform any
maneuvers within the operating limitations of the airplane;
(3) Protect the pilot from serious injury due to high energy rotating failures in systems and
equipment; and
(4) Protect the occupants from serious injury due to damage to windshields, windows, and canopies.
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(b) For level 4 airplanes, each windshield and its supporting structure directly in front of the pilot
must—
(1) Withstand, without penetration, the impact equivalent to a two-pound bird when the velocity of
the airplane is equal to the airplane’s maximum approach flap speed; and
(2) Allow for continued safe flight and landing after the loss of vision through any one panel.
(c) The airplane must provide each occupant with air at a breathable pressure, free of hazardous
concentrations of gases and vapors, during normal operations and likely failures.
(d) If an oxygen system is installed in the airplane, it must include—
(1) A means to allow the flightcrew to determine the quantity of oxygen available in each source of
supply on the ground and in flight;
(2) A means to determine whether oxygen is being delivered; and
(3) A means to permit the flightcrew to turn on and shut off the oxygen supply at any high-pressure
source in flight.
(e) If a pressurization system is installed in the airplane, it must include—
(1) A warning if an unsafe condition exists; and
(2) A pressurization system test.
FIRE AND HIGH ENERGY PROTECTION
§ 23.800 Fire protection outside designated fire zones.
Outside designated fire zones:
(a) The following materials must be self-extinguishing—
(1) Insulation on electrical wire and electrical cable;
(2) For levels 1, 2, and 3 airplanes, materials in the baggage and cargo compartments inaccessible
in flight; and
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(3) For level 4 airplanes, materials in the cockpit, cabin, baggage, and cargo compartments.
(b) The following materials must be flame resistant—
(1) For levels 1, 2 and 3 airplanes, materials in each compartment accessible in flight; and
(2) Any electrical cable installation that would overheat in the event of circuit overload or fault.
(c) Thermal acoustic materials, if installed, must not be a flame propagation hazard.
(d) Sources of heat that are capable of igniting adjacent objects must be shielded and insulated to
prevent such ignition.
(e) For level 4 airplanes, each baggage and cargo compartment must—
(1) Be located where a fire would be visible to the pilots, or equipped with a fire detection system
and warning system; and
(2) Be accessible for the manual extinguishing of a fire, have a built-in fire extinguishing system, or
be constructed and sealed to contain any fire within the compartment.
(f) There must be a means to extinguish any fire in the cabin such that—
(1) The pilot, while seated, can easily access the fire extinguishing means; and
(2) For levels 3 and 4 airplanes, passengers have a fire extinguishing means available within the
passenger compartment.
(g) Each area where flammable fluids or vapors might escape by leakage of a fluid system must—
(1) Be defined; and
(2) Have a means to make fluid and vapor ignition, and the resultant hazard, if ignition occurs,
improbable.
(h) Combustion heater installations must be protected from uncontained fire.
§ 23.805 Fire protection in designated fire zones.
Inside designated fire zones:
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(a) Flight controls, engine mounts, and other flight structures within or adjacent to those zones must
be capable of withstanding the effects of a fire.
(b) Engines must remain attached to the airplane in the event of a fire or electrical arcing.
(c) Terminals, equipment, and electrical cables used during emergency procedures must be fireresistant.
§ 23.810 Lightning protection of structure.
(a) For airplanes approved for instrument flight rules, no structural failure preventing continued
safe flight and landing may occur from exposure to the direct effects of lightning.
(b) Airplanes approved only for visual flight rules must achieve lightning protection by following
FAA accepted design practices.
Subpart E—Powerplant
§ 23.900 Powerplant installation.
(a) For the purpose of this subpart, the airplane powerplant installation must include each
component necessary for propulsion, affects propulsion safety, or provides auxiliary power to the
airplane.
(b) The applicant must construct and arrange each powerplant installation to account for likely
hazards in operation and maintenance.
(c) Except for simple airplanes, each aircraft power unit must be type certificated.
§ 23.905 Propeller installation.
(a) Except for simple airplanes, each propeller must be type certificated.
(b) Each pusher propeller must be marked so that it is conspicuous under daylight conditions.
(c) Each propeller installation must account for vibration and fatigue.
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§ 23.910 Powerplant installation hazard assessment.
The applicant must assess each powerplant separately and in relation to other airplane systems and
installations to show that a failure of any powerplant system component or accessory will not—
(a) Prevent continued safe flight and landing;
(b) Cause serious injury that may be avoided; and
(c) Require immediate action by crewmembers for continued operation of any remaining
powerplant system.
§ 23.915 Automatic power control systems.
A power or thrust augmentation system that automatically controls the power or thrust on the
operating powerplant, must—
(a) Provide indication to the flightcrew when the system is operating;
(b) Provide a means for the pilot to deactivate the automatic function; and
(c) Prevent inadvertent deactivation.
§ 23.920 Reversing systems.
The airplane must be capable of continued safe flight and landing under any available reversing
system setting.
§ 23.925 Powerplant operational characteristics.
(a) The powerplant must operate at any negative acceleration that may occur during normal and
emergency operation, within the airplane operating limitations.
(b) The pilot must have the capability to stop and restart the powerplant in flight.
(c) The airplane must have an independent power source for restarting each powerplant following
an in-flight shutdown.
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§ 23.930 Fuel system
(a) Each fuel system must—
(1) Provide an independent fuel supply to each powerplant in at least one configuration;
(2) Avoid ignition from unplanned sources;
(3) Provide the fuel required to achieve maximum power or thrust plus a margin for likely
variables, in all temperature and altitude conditions within the airplane operating envelope;
(4) Provide a means to remove the fuel from the airplane;
(5) Be capable of retaining fuel when subject to inertia loads under expected operating conditions;
and
(6) Prevent hazardous contamination of the fuel supply.
(b) Each fuel storage system must—
(1) Withstand the loads and pressures under expected operating conditions;
(2) Provide a means to prevent loss of fuel during any maneuver under operating conditions for
which certification is requested;
(3) Prevent discharge when transferring fuel;
(4) Provide fuel for at least one-half hour of operation at maximum continuous power or thrust; and
(5) Be capable of jettisoning fuel if required for landing.
(c) If a pressure refueling system is installed, it must have a means to—
(1) Prevent the escape of hazardous quantities of fuel;
(2) Automatically shut-off before exceeding the maximum fuel quantity of the airplane; and
(3) Provide an indication of a failure at the fueling station.
§ 23.935 Powerplant induction and exhaust systems.
The air induction system for each power unit and its accessories must—
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(a) Supply the air required by that power unit and its accessories under expected operating
conditions; and
(b) Provide a means to discharge potential harmful material.
§ 23.940 Powerplant ice protection.
(a) The airplane design must prevent foreseeable accumulation of ice or snow that adversely affects
powerplant operation.
(b) The powerplant design must prevent any accumulation of ice or snow that adversely affects
powerplant operation, in those icing conditions for which certification is requested.
§ 23.1000 Powerplant fire protection.
(a) A powerplant may only be installed in a designated fire zone.
(b) Each component, line, and fitting carrying flammable fluids, gases, or air subject to fire
conditions must be fire resistant, except components storing concentrated flammable material must be
fireproof or enclosed by a fireproof shield.
(c) The applicant must provide a means to shut off fuel or flammable material for each powerplant
that must—
(1) Not restrict fuel to remaining units; and
(2) Prevent inadvertent operation.
(d) For levels 3 and 4 airplanes with a powerplant located outside the pilot’s view that uses
combustible fuel, the applicant must install a fire extinguishing system.
(e) For levels 3 and 4 airplanes, the applicant must install a fire detection system in each designated
fire zone.
(f) Each fire detection system must provide a means to alert the flightcrew in the event of a
detection of fire or failure of the system.
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(g) There must be a means to check the fire detection system in flight.
Subpart F—Equipment
§ 23.1300 Airplane level systems requirements.
(a) The equipment and systems required for an airplane to operate safely in the kinds of operations
for which certification is requested (Day VFR, Night VFR, IFR) must be designed and installed to—
(1) Meet the level of safety applicable to the certification and performance level of the airplane; and
(2) Perform their intended function throughout the operating and environmental limits specified by
the applicant.
(b) Non‐required airplane equipment and systems, considered separately and in relation to other
systems, must be designed and installed so their operation or failure does not have an adverse effect on
the airplane or its occupants.
§ 23.1305 Function and installation.
(a) Each item of installed equipment must—
(1) Perform its intended function;
(2) Be installed according to limitations specified for that equipment; and
(3) Be labeled, if applicable, as to its identification, function or operating limitations, or any
combination of these factors.
(b) There must be a discernable means of providing system operating parameters required to
operate the airplane, including warnings, cautions, and normal indications to the responsible
crewmember.
(c) Information concerning an unsafe system operating condition must be provided in a timely
manner to the crewmember responsible for taking corrective action. Presentation of this information
must be clear enough to avoid likely crewmember errors.
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§ 23.1310 Flight, navigation, and powerplant instruments.
(a) Installed systems must provide the flightcrew member who sets or monitors flight parameters
for the flight, navigation, and powerplant the information necessary to do so during each phase of flight.
This information must include—
(1) Parameters and trends, as needed for normal, abnormal, and emergency operation; and
(2) Limitations, unless the applicant shows each limitation will not be exceeded in all intended
operations.
(b) Indication systems that integrate the display of flight or powerplant parameters to operate the
airplane or are required by the operating rules of this chapter must—
(1) Not inhibit the primary display of flight or powerplant parameters needed by any flightcrew
member in any normal mode of operation; and
(2) In combination with other systems, be designed and installed so information essential for
continued safe flight and landing will be available to the flightcrew in a timely manner after any single
failure or probable combination of failures.
§ 23.1315 Equipment, systems, and installations.
For any airplane system or equipment whose failure or abnormal operation has not been specifically
addressed by another requirement in this part, the applicant must:
(a) Examine the design and installation of airplane systems and equipment, separately and in
relation to other airplane systems and equipment to determine—
(1) If a failure would prevent continued safe flight and landing; and
(2) If any other failure would significantly reduce the capability of the airplane or the ability of the
flightcrew to cope with adverse operating conditions.
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(b) Design and install each system and equipment, examined separately and in relation to other
airplane systems and equipment, such that—
(1) Each catastrophic failure condition is extremely improbable;
(2) Each hazardous failure condition is extremely remote; and
(3) Each major failure condition is remote.
§ 23.1320 Electrical and electronic system lightning protection.
For an airplane approved for IFR operations:
(a) Each electrical or electronic system that performs a function, the failure of which would prevent
the continued safe flight and landing of the airplane, must be designed and installed such that—
(1) The airplane system level function continues to perform during and after the time the airplane is
exposed to lightning; and
(2) The system automatically recovers normal operation of that function in a timely manner after
the airplane is exposed to lightning unless the system’s recovery conflicts with other operational or
functional requirements of the system.
(b) Each electrical and electronic system that performs a function, the failure of which would
reduce the capability of the airplane or the ability of the flightcrew to respond to an adverse operating
condition, must be designed and installed such that the function recovers normal operation in a timely
manner after the airplane is exposed to lightning.
§ 23.1325 High-intensity Radiated Fields (HIRF) Protection.
(a) Electrical and electronic systems that perform a function, the failure of which would prevent the
continued safe flight and landing of the airplane, must be designed and installed such that—
(1) The airplane system level function is not adversely affected during and after the time the
airplane is exposed to the HIRF environment; and
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(2) The system automatically recovers normal operation of that function in a timely manner after
the airplane is exposed to the HIRF environment, unless the system’s recovery conflicts with other
operational or functional requirements of the system.
(b) For airplanes approved for IFR operations, the applicant must design and install each electrical
and electronic system that performs a function, the failure of which would reduce the capability of the
airplane or the ability of the flightcrew to respond to an adverse operating condition, so the function
recovers normal operation in a timely manner after the airplane is exposed to the HIRF environment.
§ 23.1330 System power generation, storage, and distribution.
The power generation, storage, and distribution for any system must be designed and installed to—
(a) Supply the power required for operation of connected loads during all likely operating
conditions;
(b) Ensure no single failure or malfunction will prevent the system from supplying the essential
loads required for continued safe flight and landing; and
(c) Have enough capacity, if the primary source fails, to supply essential loads, including noncontinuous essential loads for the time needed to complete the function, for—
(1) At least 30 minutes for airplanes certificated with a maximum altitude of 25,000 feet (7,620
meters) or less; and
(2) At least 60 minutes for airplanes certificated with a maximum altitude over 25,000 feet (7,620
meters).
§ 23.1335 External and cockpit lighting.
(a) The applicant must design and install all lights to prevent adverse effects on the performance of
flightcrew duties.
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(b) Any position and anti-collision lights, if required by part 91 of this chapter, must have the
intensities, flash rate, colors, fields of coverage, and other characteristics to provide sufficient time for
another aircraft to avoid a collision.
(c) Any position lights, if required by part 91 of this chapter, must include a red light on the left
side of the airplane, a green light on the right side of the airplane, spaced laterally as far apart as space
allows, and a white light facing aft, located on an aft portion of the airplane or on the wing tips.
(d) The applicant must design and install taxi and landing lights so they provide sufficient light for
night operations.
(e) For seaplanes or amphibian airplanes, riding lights must provide a white light visible in clear
atmospheric conditions.
§ 23.1400 Safety equipment.
Safety and survival equipment, required by the operating rules of this chapter, must be reliable,
readily accessible, easily identifiable, and clearly marked to identify its method of operation.
§ 23.1405 Flight in icing conditions.
(a) If an applicant requests certification for flight in icing conditions, the applicant must
demonstrate that—
(1) The ice protection system provides for safe operation; and
(2) The airplane is protected from stalling when the autopilot is operating in a vertical mode.
(b) The demonstration specified in paragraph (a) of this section, must be conducted in atmospheric
icing conditions specified in part 1 of appendix C to part 25 of this chapter, and any additional icing
conditions for which certification is requested.
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§ 23.1410 Pressurized systems elements.
(a) The minimum burst pressure of hydraulic systems must be at least 2.5 times the design
operating pressure. The proof pressure must be at least 1.5 times the maximum operating pressure.
(b) On multiengine airplanes, engine driven accessories essential to safe operation must be
distributed among multiple engines.
(c) The minimum burst pressure of cabin pressurization system elements must be at least 2.0 times,
and proof pressure must be at least 1.5 times, the maximum normal operating pressure.
(d) The minimum burst pressure of pneumatic system elements must be at least 3.0 times, and proof
pressure must be at least 1.5 times, the maximum normal operating pressure.
(e) Other pressurized system elements must have pressure margins that take into account system
design and operating conditions.
§ 23.1457 Cockpit voice recorders.
(a) Each cockpit voice recorder required by the operating rules of this chapter must be approved and
must be installed so that it will record the following:
(1) Voice communications transmitted from or received in the airplane by radio.
(2) Voice communications of flightcrew members on the flight deck.
(3) Voice communications of flightcrew members on the flight deck, using the airplane's interphone
system.
(4) Voice or audio signals identifying navigation or approach aids introduced into a headset or
speaker.
(5) Voice communications of flightcrew members using the passenger loudspeaker system, if there
is such a system and if the fourth channel is available in accordance with the requirements of paragraph
(c)(4)(ii) of this section.
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(6) If datalink communication equipment is installed, all datalink communications, using an
approved data message set. Datalink messages must be recorded as the output signal from the
communications unit that translates the signal into usable data.
(b) The recording requirements of paragraph (a)(2) of this section must be met by installing a
cockpit-mounted area microphone, located in the best position for recording voice communications
originating at the first and second pilot stations and voice communications of other crewmembers on the
flight deck when directed to those stations. The microphone must be so located and, if necessary, the
preamplifiers and filters of the recorder must be so adjusted or supplemented, so that the intelligibility of
the recorded communications is as high as practicable when recorded under flight cockpit noise
conditions and played back. Repeated aural or visual playback of the record may be used in evaluating
intelligibility.
(c) Each cockpit voice recorder must be installed so that the part of the communication or audio
signals specified in paragraph (a) of this section obtained from each of the following sources is recorded
on a separate channel:
(1) For the first channel, from each boom, mask, or handheld microphone, headset, or speaker used
at the first pilot station.
(2) For the second channel from each boom, mask, or handheld microphone, headset, or speaker
used at the second pilot station.
(3) For the third channel—from the cockpit-mounted area microphone.
(4) For the fourth channel from:
(i) Each boom, mask, or handheld microphone, headset, or speaker used at the station for the third
and fourth crewmembers.
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(ii) If the stations specified in paragraph (c)(4)(i) of this section are not required or if the signal at
such a station is picked up by another channel, each microphone on the flight deck that is used with the
passenger loudspeaker system, if its signals are not picked up by another channel.
(5) And that as far as is practicable all sounds received by the microphone listed in paragraphs
(c)(1), (2), and (4) of this section must be recorded without interruption irrespective of the position of
the interphone-transmitter key switch. The design shall ensure that sidetone for the flightcrew is
produced only when the interphone, public address system, or radio transmitters are in use.
(d) Each cockpit voice recorder must be installed so that:
(1) (i) It receives its electrical power from the bus that provides the maximum reliability for
operation of the cockpit voice recorder without jeopardizing service to essential or emergency loads.
(ii) It remains powered for as long as possible without jeopardizing emergency operation of the
airplane.
(2) There is an automatic means to simultaneously stop the recorder and prevent each erasure
feature from functioning, within 10 minutes after crash impact.
(3) There is an aural or visual means for preflight checking of the recorder for proper operation.
(4) Any single electrical failure external to the recorder does not disable both the cockpit voice
recorder and the flight data recorder.
(5) It has an independent power source—
(i) That provides 10 ±1 minutes of electrical power to operate both the cockpit voice recorder and
cockpit-mounted area microphone;
(ii) That is located as close as practicable to the cockpit voice recorder; and
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(iii) To which the cockpit voice recorder and cockpit-mounted area microphone are switched
automatically in the event that all other power to the cockpit voice recorder is interrupted either by
normal shutdown or by any other loss of power to the electrical power bus.
(6) It is in a separate container from the flight data recorder when both are required. If used to
comply with only the cockpit voice recorder requirements, a combination unit may be installed.
(e) The recorder container must be located and mounted to minimize the probability of rupture of
the container as a result of crash impact and consequent heat damage to the recorder from fire.
(1) Except as provided in paragraph (e)(2) of this section, the recorder container must be located as
far aft as practicable, but need not be outside of the pressurized compartment, and may not be located
where aft-mounted engines may crush the container during impact.
(2) If two separate combination digital flight data recorder and cockpit voice recorder units are
installed instead of one cockpit voice recorder and one digital flight data recorder, the combination unit
that is installed to comply with the cockpit voice recorder requirements may be located near the cockpit.
(f) If the cockpit voice recorder has a bulk erasure device, the installation must be designed to
minimize the probability of inadvertent operation and actuation of the device during crash impact.
(g) Each recorder container must—
(1) Be either bright orange or bright yellow;
(2) Have reflective tape affixed to its external surface to facilitate its location under water; and
(3) Have an underwater locating device, when required by the operating rules of this chapter, on or
adjacent to the container, which is secured in such manner that they are not likely to be separated during
crash impact.
§ 23.1459 Flight data recorders
(a) Each flight recorder required by the operating rules of this chapter must be installed so that—
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(1) It is supplied with airspeed, altitude, and directional data obtained from sources that meet the
aircraft level system requirements of § 23.1300 and the functionality specified in § 23.1305;
(2) The vertical acceleration sensor is rigidly attached, and located longitudinally either within the
approved center of gravity limits of the airplane, or at a distance forward or aft of these limits that does
not exceed 25 percent of the airplane's mean aerodynamic chord;
(3) (i) It receives its electrical power from the bus that provides the maximum reliability for
operation of the flight data recorder without jeopardizing service to essential or emergency loads;
(ii) It remains powered for as long as possible without jeopardizing emergency operation of the
airplane;
(4) There is an aural or visual means for preflight checking of the recorder for proper recording of
data in the storage medium;
(5) Except for recorders powered solely by the engine-driven electrical generator system, there is an
automatic means to simultaneously stop a recorder that has a data erasure feature and prevent each
erasure feature from functioning, within 10 minutes after crash impact;
(6) Any single electrical failure external to the recorder does not disable both the cockpit voice
recorder and the flight data recorder; and
(7) It is in a separate container from the cockpit voice recorder when both are required. If used to
comply with only the flight data recorder requirements, a combination unit may be installed. If a
combination unit is installed as a cockpit voice recorder to comply with § 23.1457(e)(2), a combination
unit must be used to comply with this flight data recorder requirement.
(b) Each non-ejectable record container must be located and mounted so as to minimize the
probability of container rupture resulting from crash impact and subsequent damage to the record from
fire. In meeting this requirement, the record container must be located as far aft as practicable, but need
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not be aft of the pressurized compartment, and may not be where aft-mounted engines may crush the
container upon impact.
(c) A correlation must be established between the flight recorder readings of airspeed, altitude, and
heading and the corresponding readings (taking into account correction factors) of the first pilot's
instruments. The correlation must cover the airspeed range over which the airplane is to be operated, the
range of altitude to which the airplane is limited, and 360 degrees of heading. Correlation may be
established on the ground as appropriate.
(d) Each recorder container must—
(1) Be either bright orange or bright yellow;
(2) Have reflective tape affixed to its external surface to facilitate its location under water; and
(3) Have an underwater locating device, when required by the operating rules of this chapter, on or
adjacent to the container, which is secured in such a manner that they are not likely to be separated
during crash impact.
(e) Any novel or unique design or operational characteristics of the aircraft shall be evaluated to
determine if any dedicated parameters must be recorded on flight recorders in addition to or in place of
existing requirements.
Subpart G—Flightcrew Interface and Other Information
§ 23.1500 Flightcrew interface.
(a) The pilot compartment and its equipment must allow each pilot to perform his or her duties,
including taxi, takeoff, climb, cruise, descent, approach, landing, and perform any maneuvers within the
operating envelope of the airplane, without excessive concentration, skill, alertness, or fatigue.
(b) The applicant must install flight, navigation, surveillance, and powerplant controls and displays
so qualified flightcrew can monitor and perform all tasks associated with the intended functions of
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systems and equipment. The system and equipment design must make the possibility that a flightcrew
error could result in a catastrophic event highly unlikely.
§23.1505 Instrument markings, control markings, and placards.
(a) Each airplane must display in a conspicuous manner any placard and instrument marking
necessary for operation.
(b) The applicant must clearly mark each cockpit control, other than primary flight controls, as to its
function and method of operation.
(c) The applicant must include instrument marking and placard information in the Airplane Flight
Manual.
§ 23.1510 Airplane flight manual.
The applicant must provide an Airplane Flight Manual that must be delivered with each airplane
that contains the following information—
(a) Operating limitations and procedures;
(b) Performance information;
(c) Loading information; and
(d) Any other information necessary for the operation of the airplane.
§ 23.1515 Instructions for Continued Airworthiness.
The applicant must prepare Instructions for Continued Airworthiness, in accordance with appendix
A of this part, that are acceptable to the Administrator prior to the delivery of the first airplane or
issuance of a standard certification of airworthiness, whichever occurs later.
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APPENDIX A TO PART 23—INSTRUCTIONS FOR CONTINUED AIRWORTHINESS
A23.1 General.
(a) This appendix specifies requirements for the preparation of Instructions for Continued
Airworthiness as required by this part.
(b) The Instructions for Continued Airworthiness for each airplane must include the Instructions for
Continued Airworthiness for each engine and propeller (hereinafter designated “products”), for each
appliance required by this chapter, and any required information relating to the interface of those
appliances and products with the airplane. If Instructions for Continued Airworthiness are not supplied
by the manufacturer of an appliance or product installed in the airplane, the Instructions for Continued
Airworthiness for the airplane must include the information essential to the continued airworthiness of
the airplane.
(c) The applicant must submit to the FAA a program to show how changes to the Instructions for
Continued Airworthiness made by the applicant or by the manufacturers of products and appliances
installed in the airplane will be distributed.
A23.2 Format.
(a) The Instructions for Continued Airworthiness must be in the form of a manual or manuals as
appropriate for the quantity of data to be provided.
(b) The format of the manual or manuals must provide for a practical arrangement.
A23.3 Content.
The contents of the manual or manuals must be prepared in the English language. The Instructions
for Continued Airworthiness must contain the following manuals or sections and information:
(a) Airplane maintenance manual or section.
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(1) Introduction information that includes an explanation of the airplane's features and data to the
extent necessary for maintenance or preventive maintenance.
(2) A description of the airplane and its systems and installations including its engines, propellers,
and appliances.
(3) Basic control and operation information describing how the airplane components and systems
are controlled and how they operate, including any special procedures and limitations that apply.
(4) Servicing information that covers details regarding servicing points, capacities of tanks,
reservoirs, types of fluids to be used, pressures applicable to the various systems, location of access
panels for inspection and servicing, locations of lubrication points, lubricants to be used, equipment
required for servicing, tow instructions and limitations, mooring, jacking, and leveling information.
(b) Maintenance Instructions.
(1) Scheduling information for each part of the airplane and its engines, auxiliary power units,
propellers, accessories, instruments, and equipment that provides the recommended periods at which
they should be cleaned, inspected, adjusted, tested, and lubricated, and the degree of inspection, the
applicable wear tolerances, and work recommended at these periods. However, the applicant may refer
to an accessory, instrument, or equipment manufacturer as the source of this information if the applicant
shows that the item has an exceptionally high degree of complexity requiring specialized maintenance
techniques, test equipment, or expertise. The recommended overhaul periods and necessary cross
reference to the Airworthiness Limitations section of the manual must also be included. In addition, the
applicant must include an inspection program that includes the frequency and extent of the inspections
necessary to provide for the continued airworthiness of the airplane.
(2) Troubleshooting information describing probable malfunctions, how to recognize those
malfunctions, and the remedial action for those malfunctions.
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(3) Information describing the order and method of removing and replacing products and parts with
any necessary precautions to be taken.
(4) Other general procedural instructions including procedures for system testing during ground
running, symmetry checks, weighing and determining the center of gravity, lifting and shoring, and
storage limitations.
(c) Diagrams of structural access plates and information needed to gain access for inspections when
access plates are not provided.
(d) Details for the application of special inspection techniques including radiographic and ultrasonic
testing where such processes are specified by the applicant.
(e) Information needed to apply protective treatments to the structure after inspection.
(f) All data relative to structural fasteners such as identification, discard recommendations, and
torque values.
(g) A list of special tools needed.
(h) In addition, for level 4 airplanes, the following information must be furnished—
(1) Electrical loads applicable to the various systems;
(2) Methods of balancing control surfaces;
(3) Identification of primary and secondary structures; and
(4) Special repair methods applicable to the airplane.
A23.4 Airworthiness limitations section.
The Instructions for Continued Airworthiness must contain a section titled Airworthiness
Limitations that is segregated and clearly distinguishable from the rest of the document. This section
must set forth each mandatory replacement time, structural inspection interval, and related structural
inspection procedure required for type certification. If the Instructions for Continued Airworthiness
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consist of multiple documents, the section required by this paragraph must be included in the principal
manual. This section must contain a legible statement in a prominent location that reads "The
Airworthiness Limitations section is FAA approved and specifies maintenance required under §§ 43.16
and 91.403 of Title 14 of the Code of Federal Regulations unless an alternative program has been FAA
approved."
PART 35—AIRWORTHINESS STANDARDS: PROPELLERS
9. The authority citation for part 35 is revised to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704.
10. In § 35.1, revise paragraph (c) to read as follows:
§ 35.1 Applicability.
*
*
*
*
*
(c) An applicant is eligible for a propeller type certificate and changes to those certificates after
demonstrating compliance with subparts A, B, and C of this part. However, the propeller may not be
installed on an airplane unless the applicant has shown compliance with either § 23.905(c) or § 25.907
of this chapter, as applicable, or compliance is not required for installation on that airplane.
*
*
*
*
*
11. In § 35.37, revise paragraph (c)(1) to read as follows:
§ 35.37 Fatigue limits and evaluation
*
*
*
*
*
(c) * * *
(1) The intended airplane by complying with § 23.905(c) or § 25.907 of this chapter, as applicable;
or
*
*
*
*
*
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PART 43—MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND
ALTERATION
12. The authority citation for part 43 is revised to read as follows:
Authority: 42 U.S.C. 7572; 49 U.S.C. 106(f), 106(g), 40105, 40113, 44701-44702, 44704, 44707,
44709, 44711, 44713, 44715, 45303.
13. In part 43, appendix E, revise the introductory paragraph and paragraph (a)(2) to read as
follows:
Appendix E to Part 43—Altimeter System Test and Inspection
Each person performing the altimeter system tests and inspections required by § 91.411 must
comply with the following:
(a) * * *
(2) Perform a proof test to demonstrate the integrity of the static pressure system in a manner
acceptable to the Administrator. For airplanes certificated under part 25 of this chapter, determine that
leakage is within the tolerances established by § 25.1325.
*
*
*
*
*
PART 91—GENERAL OPERATING AND FLIGHT RULES
14. The authority citation for part 91 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 1155, 40101, 40103, 40105, 40113, 40120, 44101, 44111,
44701, 44704, 44709, 44711, 44712, 44715, 44716, 44717, 44722, 46306, 46315, 46316, 46504, 4650646507, 47122, 47508, 47528-47531, 47534, articles 12 and 29 of the Convention on International Civil
Aviation (61 Stat. 1180), (126 Stat. 11).
15. In § 91.205, revise paragraphs (b)(13) and (b)(14), and remove paragraph (b)(16) to read as
follows:
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§ 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates:
Instrument and equipment requirements.
*
*
*
*
*
(b) * * *
(13) An approved safety belt with an approved metal-to-metal latching device, or other approved
restraint system for each occupant 2 years of age or older.
(14) For small civil airplanes manufactured after July 18, 1978, an approved shoulder harness or
restraint system for each front seat. For small civil airplanes manufactured after December 12, 1986, an
approved shoulder harness or restraint system for all seats. Shoulder harnesses installed at flightcrew
stations must permit the flightcrew member, when seated and with the safety belt and shoulder harness
fastened, to perform all functions necessary for flight operations. For purposes of this paragraph—
(i) The date of manufacture of an airplane is the date the inspection acceptance records reflect that
the airplane is complete and meets the FAA-approved type design data; and
(ii) A front seat is a seat located at a flightcrew member station or any seat located alongside such a
seat.
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16. In § 91.313, revise paragraph (g) introductory text to read as follows:
§ 91.313 Restricted category civil aircraft: Operating limitations.
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(g) No person may operate a small restricted-category civil airplane manufactured after July 18,
1978, unless an approved shoulder harness or restraint system is installed for each front seat. The
shoulder harness or restraint system installation at each flightcrew station must permit the flightcrew
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member, when seated and with the safety belt and shoulder harness fastened or the restraint system
engaged, to perform all functions necessary for flight operation. For purposes of this paragraph—
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17. In § 91.323 revise paragraph (b)(3) to read as follows:
§ 91.323 Increased maximum certificated weights for certain airplanes operated in Alaska.
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(b) * * *
(3) The weight at which the airplane meets the positive maneuvering load factor n, where
n=2.1+(24,000/(W+10,000)) and W=design maximum takeoff weight, except that n need not be more
than 3.8; or
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18. In § 91.531, revise paragraphs (a)(1) and (a)(3) to read as follows:
§ 91.531 Second in command requirements.
(a) * * *
(1) A large airplane or normal category level 4 airplane, except that a person may operate an
airplane certificated under SFAR 41 without a pilot who is designated as second in command if that
airplane is certificated for operation with one pilot.
***
(3) A commuter category airplane or normal category level 3 airplane, except that a person may
operate those airplanes notwithstanding paragraph (a)(1) of this section, that have a passenger seating
configuration, excluding pilot seats, of nine or less without a pilot who is designated as second in
command if that airplane is type certificated for operations with one pilot.
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PART 121—OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL
OPERATIONS
19. The authority citation for part 121 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40103, 40113, 40119, 41706, 42301 preceding note added by
Pub. L. 112-95, Sec. 412, 126 Stat. 89, 44101, 44701-44702, 44705, 44709-44711, 44713, 44716-44717,
44722, 44729, 44732; 46105; Pub. L. 111-216, 124 Stat. 2348 (49 U.S.C. 44701 note); Pub. L. 112-95,
126 Stat. 62 (49 U.S.C. 44732 note).
20. In § 121.310, revise paragraph (b)(2)(iii) to read as follows:
§ 121.310 Additional emergency equipment.
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*
(b) * * *
(2) * * *
(iii) For a nontransport category turbopropeller powered airplane type certificated after December
31, 1964, each passenger emergency exit marking and each locating sign must be manufactured to meet
the requirements of § 23.811(b) of this chapter in effect on June 16, 1994. On these airplanes, no sign
may continue to be used if its luminescence (brightness) decreases to below 100 microlamberts.
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PART 135—OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND
OPERATIONS AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT
21. The authority citation for part 135 continues to read as follows:
Authority: 49 U.S.C. 106(f), 106(g), 41706, 40113, 44701-44702, 44705, 44709, 44711-44713,
44715-44717, 44722, 44730, 45101-45105; Pub. L. 112-95, 126 Stat. 58 (49 U.S.C. 44730).
22. In § 135.169, revise paragraphs (b) introductory text, (b)(6), and (b)(7), and add paragraph
(b)(8) to read as follows:
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§ 135.169 Additional airworthiness requirements.
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(b) No person may operate a small airplane that has a passenger seating configuration, excluding
pilot seats, of 10 seats or more unless it is type certificated—
* *
*
(6) In the normal category and complies with section 1.(b) of Special Federal Aviation Regulation
No. 41;
(7) In the commuter category; or
(8) In the normal category, using a means of compliance accepted by the Administrator equivalent
to the airworthiness standards applicable to the certification of airplanes in the commuter category found
in part 23 of this chapter through amendment 23-62, effective January 31, 2012.
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*
Issued under authority provided by 49 U.S.C. 106(f), 44701(a), 44703 and Pub. L. 113-53 (127 Stat.
584; 49 U.S.C. 44704 note) in Washington, DC, on March 7, 2016.
Dorenda D. Baker
Director, Aircraft Certification Service.
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